THE  LIBRARY 

OF 

THE  UNIVERSITY 
OF  CALIFORNIA 

LOS  ANGELES 


The  RALPH  D.  REED  LIBRARY 

DEPARTMENT  OF  GEOLOOY 

UNIVERSITY  OF  CALIFORNIA 

LOS  ANGELES,  CALIF. 


Robert  W.  Webb. 


ROBERT  W.  WEBB 
GEOLOGY  DEPT.,  U.C.L.A; 


^ 


ECONOMIC  GEOLOGY 

OP  THE 

UNITED   STATES 


ECONOMIC    GEOLOGY 


OF  THE 


UNITED    STATES 


BY 


HEINRICH  RIES,  A.M.,  PH.D. 

PHOFESSOR  OF  ECONOMIC  GEOLOGY  AT  CORNELL 
UNIVERSITY 


THE  MACMILLAN   COMPANY 

LONDON:  MACMILLAN  &  CO.,  LTD. 

1908 
All  rights  reserved 


COPYRIGHT,  1905,  1907, 
BY  THE  MACMILLAN  COMPANY. 


Set  up  and  electrotyped.     Published  November,  1905. 
New  edition  January,  1907  ;  February,  1908. 


Norton  oft  I3rcsa 

J.  8.  Cashing  &  Co.  —  Berwick  &  Smith  Co. 
Norwood,  Maas.,  U.S.A. 


Library 

TV 


PREFACE 

THE  following  work  on  the  Economic  Geology  of  the 
United  States  covers  essentially  the  ground  which  is  gone 
over  in  the  elementary  course  in  this  subject  in  Cornell 
University,  but  it  is  hoped  that  it  will  prove  useful  as  a 
text-book  in  other  colleges. 

The  mode  of  arrangement  is  markedly  different  from  that 
found  in  other  books  on  the  same  subject,  in  that  the  non- 
metallic  minerals  are  discussed  first  and  the  metallic  minerals 
last.  This,  to  the  author,  seems  the  most  desirable  method 
of  treatment,  for  the  reason  that  the  non-metallics  are  not 
only  the  most  important,  the  value  of  their  production 
having  exceeded  the  metallics  by  over  one  hundred  and 
fifty  million  dollars  in  1903,  but  also  because  it  leads  from 
a  discussion  of  the  simpler  to  the  more  complex  forms  of 
mineral  deposits. 

It  has  not  been  thought  desirable  to  include  a  chapter  on 
geologic  and  physiographic  principles,  since  the  space  which 
could  be  allotted  to  it  is  altogether  too  small,  and,  more- 
over, the  study  of  economic  geology  presupposes  a  knowl- 
edge of  geology  and  mineralogy  on  the  part  of  the  student. 
While  the  references  given  at  the  end  of  each  chapter  do 
not  include  every  paper  that  has  been  written  on  the  subject 
to  which  they  refer,  still  it  is  believed  that  they  are  suffi- 
ciently numerous  to  permit  one  to  follow  out  the  subject  in 
considerable  detail  if  he  so  desire. 

In  the  preparation  of  the  manuscript  all  available  sources 
of  information  have  been  freely  drawn  upon,  and  the  num- 
bers in  parentheses  in  the  text  refer  to  the  numbered  refer- 
ences at  the  end  of  each  chapter. 


562949 


Vi  PKEFACE 

All  statistical  figures,  unless  otherwise  stated,  are  taken 
from  the  reports  of  the  United  States  Geological  Survey. 

Descriptions  of  mineral  occurrences  in  foreign  countries 
are  not  included,  except  in  a  few  cases  where  the  deposits 
serve  as  an  important  if  not  the  only  source  of  supply  for 
the  United  States. 

The  writer  wishes  to  express  his  thanks  to  Professor  R.  S. 
Tarr  for  examination  and  criticism  of  much  of  the  manu- 
script, and  to  W.  E.  McCourt,  Instructor  in  Geology,  and 
H.  Leighton,  Assistant  in  Geology,  for  aid  in  the  preparation 
of  drawings  and  statistical  tables.  For  the  loan  of  photo- 
graphs or  cuts  acknowledgments  are  due  to  Messrs.  H.  F. 
Bain,  J.  E.  Spurr,  J.  M.  Boutwell,  G.  H.  Eldridge,  W.  Lind- 
gren,  F.  H.  Oliphant,  and  J.  H.  Pratt  of  the  United  States 
Geological  Survey ;  Professor  A.  C.  Lane,  Michigan  Geologi- 
cal Survey;  Dr.  D.  H.  Newland,  New  York  State  Museum; 
Professor  C.  C.  O'Harra,  South  Dakota  School  of  Mines; 
Professor  E.  A.  Smith,  Alabama  Geological  Survey ;  Pro- 
fessor G.  H.  Perkins,  Vermont  Geological  Survey ;  Dr.  H.  B. 
Kiimmel,  New  Jersey  Geological  Survey ;  Dr.  W.  B.  Phillips, 
Texas  Geological  Survey ;  Dr.  G.  P.  Merrill,  United  States 
National  Museum;  also  to  Messrs.  H.  W.  Turner,  F.  S. 
Witherbee,  A.  W.  Sheafer,  L.  Martin,  Wiley  &  Sons,  Ver- 
mont Marble  Co.,  and  Bedford  Quarries  Co. 

CORNELL  UNIVERSITY, 
ITHACA,  N.Y.,  June,  1905. 


PREFACE  TO  THE  SECOND  EDITION 

THE  publication  of  a  second  edition  has  become  necessary 
in  such  a  comparatively  short  time,  that  it  has  not  been 
deemed  advisable  to  materially  alter  the  text.  An  attempt 
has,  however,  been  made  to  correct  all  errors  of  which  the 
author  has  knowledge.  Recognizing  the  value  of  fresh 
statistics,  those  for  1905  (the  most  recent  available)  have 
been  given  in  an  appendix,  and  for  the  benefit  of  those  who 
make  use  of  the  bibliography,  a  second  appendix  has  been 
included,  containing  a  list  of  the  more  important  papers 
published  since  the  appearance  of  the  first  edition. 

CORNELL  UNIVERSITY, 

ITHACA,  N.Y.,  Nov.  10,  1906. 


vii 


CONTENTS 

FAGK 

PREFACE          v 

CONTENTS vii 

LIST  OF  ILLUSTRATIONS xv 

LIST  OF  ABBREVIATIONS zxi 

PART  I 

NON-METALLIC  MINERALS 

CHAPTER  I 

COAL 3-38 

Kinds  of  coal,  3  ;  Peat,  3  ;  Lignite,  4  ;  Bituminous  coal,  4  ;  Cannel 
coal,  5 :  Semi-bituminous  coal,  5 ;  Anthracite  coal,  5 ;  Proximate 
analysis  of  coal,  6 ;  Origin  of  coal,  9 ;  Conditions  of  vegetable 
accumulation,  10  ;  Chemical  changes  occurring  during  coal  forma- 
tion, 12 ;  Effect  of  heat  and  pressure,  14 ;  Structural  features  of 
coal  beds,  15;  Outcrops,  15;  Associated  rocks,  16;  Variations  in 
thickness,  16  ;  Other  irregularities,  17  ;  Coal  fields  of  the  United 
States,  18;  Geologic  distribution  of  coals  in  the  United  States,  19 ; 
Appalachian  field,  20 ;  Bituminous  area,  21 ;  Character  of  Appa- 
lachian bituminous  coals,  22  ;  Pennsylvania  anthracite  field,  22 ; 
Rhode  Island  field,  25 ;  The  Triassic  field,  25 ;  Eastern  Interior 
field,  26 ;  Northern  Interior  field,  27  ;  Western  Interior  field  and 
southwestern  fields,  28  ;  Western  Interior  field,  29 ;  Southwestern 
field,  29  ;  Gulf  states  lignite  area,  30  ;  Rocky  Mountain  fields,  30  ; 
The  Pacific  Coast  fields,  31 ;  Alaska,  32 ;  Production  of  coal,  33 ; 
Production  of  coke,  35;  References  on  coal,  35;  References  on 
peat,  38. 

CHAPTER  II 

PETROLEUM,  NATURAL  GAS,  AND  OTHER  HYDROCARBONS     .        .          39-68 

History  of  petroleum  development,  39 ;  History  of  natural  gas 
development,  40  ;  Properties  of  petroleum,  40;  Properties  of  natural 
gas,  42  ;  Mode  of  occurrence,  43  ;  Pressure  of  oil  and  gas  wells,  44  ; 
Origin,  46 ;  Inorganic  theory,  46 ;  Organic  theory,  47  ;  Geological 


X  CONTENTS 

PAGE 

distribution  of  petroleum  and  natural  gas,  48 ;  Distribution  of 
petroleum  in  the  United  States,  48  ;  Appalachian  field,  48 ;  Ohio- 
Indiana  field,  60 ;  Texas-Louisiana  oil  fields,  51 ;  Kansas,  62  ;  Cali- 
fornia, 62  ;  Wyoming,  63 ;  Colorado,  53 ;  Alaska,  54  ;  Distribution 
of  natural  gas  in  the  United  States,  54 ;  New  York,  64 ;  Pennsyl- 
vania, 54  ;  West  Virginia,  55  ;  Ohio,  55  ;  Indiana,  55  ;  Kansas,  55 ; 
Uses  of  petroleum,  66 ;  Uses  of  natural  gas,  56 ;  Oil  shales,  66 ; 
Solid  bitumens,  57  ;  Occurrence,  57 ;  Asphaltites,  58 ;  Albertite, 
59 ;  Anthraxolite,  69  ;  Ozokerite,  59  ;  Grahamite,  59  ;  Lake  asphalt, 
69  ;  Uintaite  or  gilsonite,  59  ;  Manjak,  59  ;  Bituminous  rocks,  60  ; 
Analyses,  60 ;  Uses,  61 ;  Production  of  petroleum,  natural  gas, 
and  asphaltum,  61 ;  References  on  petroleum,  66 ;  References  on 
natural  gas,  67 ;  References  on  oil  shale,  67 ;  References  on  as- 
phaltum, 67. 

CHAPTER    III 

BUILDING  STONES 69-91 

Properties  of  building  stones,  69 ;  Color,  70  ;  Texture,  70 ;  Den- 
sity, 70 ;  Hardness,  71 ;  Strength,  71 ;  Crushing  strength,  72 ; 
Transverse  strength,  72 ;  Porosity  and  ratio  of  absorption,  73 ; 
Resistance  to  frost,  73  ;  Resistance  to  heat,  73  ;  Structural  features 
affecting  quarrying,  74 ;  Bedding  planes,  74 ;  Granites,  75 ;  Char- 
acteristics of  granites,  75 ;  Distribution  of  granites  in  the  United 
States,  76  ;  Eastern  crystalline  belt,  77  ;  Central  states,  77  ;  West- 
ern states,  77;  Uses  of  granite,  77;  Miscellaneous  igneous  rocks, 
78 ;  Limestones  and  marbles,  78 ;  General  characteristics,  78 ; 
Varieties  of  limestones,  79 ;  Distribution  of  limestones  in  the 
United  States,  80 ;  Distribution  of  marbles  in  the  United  States, 
81 ;  Onyx  marbles,  83 ;  Serpentine,  83 ;  Sandstones,  84 ;  General 
properties,  84 ;  Varieties  of  sandstone,  85 ;  Distribution  of  sand- 
stones in  the  United  States,  86 ;  Uses  of  sandstones,  87 ;  Slates, 
87 ;  General  characteristics,  87 ;  Distribution  of  slates  in  the 
United  States,  88;  Uses  of  slate,  89;  Production  of  building 
stones,  89 ;  References  on  building  stones,  90 ;  References  on 
onyx  marble,  91. 

CHAPTER  IV 

CLAY 92-108 

Definition,  92 ;  Residual  clays,  92 ;  Sedimentary  clays,  93 ; 
Marine  clays,  94 ;  Flood-plain  clays,  94 ;  Lake  clays,  94 ;  Glacial 
clays,  94;  jEolian  clays,  94;  Properties  of  clay,  95;  Chemical 
properties,  95;  Physical  properties,  96;  Plasticity,  96;  Tensile 
strength,  96 ;  Shrinkage,  96 ;  Fusibility,  97  ;  Specific  gravity,  97 ; 


CONTENTS  xi 

PAOK 

Chemical  composition,  97 ;  Classification  of  clay,  98 ;  Kinds  of 
clay,  99  ;  Geological  distribution,  100  ;  Distribution  of  clays  in  the 
United  States  by  kinds,  100  ;  Kaolins,  100 ;  Fire  clays,  102 ;  Pot- 
tery clays,  103 ;  Brick  and  tile  clays,  104 ;  Miscellaneous  clays  of 
importance,  104 ;  Uses  of  clay,  105 ;  Production  of  clay,  105 ; 
Eeferences  on  clay,  106. 

CHAPTER  V 

LIME  AND  CALCAREOUS  CEMENTS 109-123 

Composition  of  limestone,  109  ;  Changes  in  burning,  110  ;  Lime, 
110 ;  Hydraulic  cements,  111  ;  Pozzuolano  cements,  111 ;  Hy- 
draulic limes,  112  ;  Natural  rock  cements,  112 ;  Portland  cement, 
113  ;  Distribution  of  lime  and  cement  materials  in  the  United  States, 
116  ;  Limestone  for  lime,  116  ;  Hydraulic  limes,  117  ;  Natural  rock 
cement,  117 ;  Portland  cements,  118 ;  Uses  of  lime,  119 ;  Uses  of 
cement,  119  ;  Production  of  cement,  120  ;  References  on  lime  and 
cement  materials,  121. 

CHAPTER  VI 

SALINES 124-138 

Salt,  124  ;  Occurrence  of  salt  in  sea  and  lake  waters,  124  ;  Rock 
salt,  125 ;  Origin  of  rock  salt,  125 ;  Natural  brines,  127 ;  Salt 
marshes  and  soils,  127  ;  Distribution  of  salt  in  the  United  States, 
127;  New  York,  127;  Michigan,  129;  Other  eastern  states,  129; 
Louisiana,  129  ;  Kansas,  130  ;  Other  western  states,  130 ;  Extrac- 
tion, 131 ;  Uses,  132  ;  Production  of  salt,  132 ;  References  on  salt, 
134;  Borax,  134;  Borax  minerals,  134;  Distribution  in  United 
States,  134  ;  Uses,  134 ;  Production  of  borax,  136 ;  References  on 
borax,  136 ;  Sodium  sulphate,  136;  References,  137 ;  Sodium  car- 
bonate, 137  ;  References,  137  ;  Soda  niter,  137  ;  References,  138. 

CHAPTER  VH 

GYPSUM 139-146 

Gypsum,  139  ;  Anhydrite,  139  ;  Origin  of  gypsum,  139 ;  Gypsite, 
140 ;  Distribution  in  the  United  States,  140 ;  Iowa,  140 ;  Kansas, 
141 ;  Michigan,  142  ;  New  York,  142  ;  Other  occurrences,  142 ; 
Analyses,  143  ;  Uses,  143  ;  Production  of  gypsum,  145  ;  References 
on  gypsum,  146. 

CHAPTER  Vm 

FERTILIZEBS    .        .        .        .        .        .        .        .      .  *        .;       .      147-167 

Phosphate  of  lime,  147 ;  Apatite,  147  ;  Amorphous  phosphates, 
147 ;  Florida  phosphates,  148 ;  Land  pebble  or  matrix  rock,  149 ; 


CONTENTS 

PAGS 

River  pebble,  149 ;  South  Carolina  phosphates,  150 ;  Tennessee 
phosphates,  160;  Other  phosphate  occurrences,  153;  Composition, 
153  ;  Uses,  154 ;  Guano,  156 ;  Greensand,  155 ;  Production,  156 ; 
References  on  fertilizers,  157. 


CHAPTER  IX 

ABRASIVES 158-166 

Introductory,  158  ;  Grindstones,  158 ;  Whetstones  and  oilstones, 
159 ;  Buhrstones  and  millstones,  161 ;  Pumice  and  volcanic  ash, 
161 ;  Infusorial  earth  and  tripoli,  162  ;  Crystalline  quartz,  163 ; 
Garnet,  163 ;  Corundum  and  emery,  163  ;  Artificial  abrasives,  165  ; 
Production  of  abrasives,  165  ;  References  on  abrasives,  166. 


CHAFIER  X 

MINOR  MINERALS 167-203 

Asbestos,  167  ;  Asbestos  minerals,  167  ;  Distribution,  167  ;  Uses, 
169 ;  Production  of  asbestos,  169 ;  References  on  asbestos,  169 ; 
Barite,  170 ;  Uses,  170 ;  Production,  170 ;  References  on  barite, 
171 ;  Fluorspar,  171 ;  Distribution  in  United  States,  172  ;  Uses,  173  ; 
References  on  fluorspar,  174 ;  Fuller's  earth,  174 ;  Production  of 
fuller's  earth,  176 ;  References  on  fuller's  earth,  176  ;  Glass  sand, 
176 ;  References  on  glass  sand,  178 ;  Graphite,  178  ;  Distribution 
of  graphite  in  the  United  States,  178 ;  Uses,  179 ;  Production  of 
graphite,  180 ;  References  on  graphite,  181 ;  Lithographic  stone, 
181  ;  References  on  lithographic  stone,  183 ;  Lithium,  183 ;  Mag- 
nesite,  183 ;  References  on  magnesite,  184  ;  Mica,  184  ;  References 
on  mica,  186 ;  Mineral  pigments,  186  ;  Hematite,  186  ;  Ochers,  186  ; 
Slate,  187  ;  Gypsum,  187  ;  Barite,  187  ;  Asbestos,  188 ;  Graphite, 
188 ;  Calcium  carbonate,  188 ;  Other  paints,  188 ;  Production  of 
mineral  pigments,  189 ;  References  on  mineral  paints,  189 ;  Mold- 
ing sand,  189 ;  References  on  molding  sand,  190 ;  Monazite,  190 ; 
Uses,  191 ;  Production  of  monazite,  191 ;  References  on  monazite, 
191 ;  Precious  stones,  192 ;  Diamond,  192  ;  Ruby,  193  ;  Sapphire, 
193  ;  Emerald,  193  ;  Topaz,  194 ;  Turquoise,  194  ;  Garnet,  194 ; 
Opal,  195 ;  Other  precious  stones,  195 ;  Production  of  precious 
stones,  196 ;  References  on  precious  stones,  196 ;  Sulphur  and 
pyrite,  196 ;  Sulphur,  196  ;  Solfataric  type,  196  ;  Gypsum  type,  197  ; 
Uses,  198;  Production  of  sulphur,  198;  References  on  sulphur, 
199 ;  Pyrite,  199 ;  Distribution,  199 ;  Uses,  200 ;  References  on 
pyrite,  200 ;  Strontium,  200 ;  Uses,  201  ;  References  on  strontium, 
201 ;  Talc  and  soapstone,  201 ;  Uses,  202 ;  Pyrophyllite,  203 ; 
Production,  203 ;  References  on  talc  and  soapstone,  203. 


CONTENTS  Xlll 

CHAPTER  XI 

PAGE 

WATER 204-212 

Mineral  waters,  204;  Distribution  of  mineral  waters  in  the 
United  States,  205  ;  Production  of  mineral  waters,  206  ;  References 
on  mineral  waters,  207  ;  Underground  waters,  207  ;  Ground  water, 
207  ;  Artesian  waters,  209 ;  References  on  underground  water,  211. 


CHAPTER  XII 

SOILS  AND  ROAD  MATERIALS 213-219 

Soils,  213 ;  Origin,  213 ;  Residual  soils,  213 ;  Transported  soils, 
213 ;  Properties  of  soils,  213  ;  Chemical  properties,  214 ;  Physical 
properties,  215 ;  Distribution  of  soils  in  the  United  States,  216 ; 
References  on  soils,  216  ;  Road  materials,  217  ;  References  on  road 
materials,  219. 


PAET  II 
METALLIC  MINERALS  OR   ORES 

CHAPTER  XIII 

ORE  DEPOSITS 223-250 

Definition,  223 ;  Gangue  minerals,  223 ;  Origin  of  ore  bodies, 
224 ;  Ores  of  contemporaneous  origin,  224 ;  Concentration  of  ores 
in  rocks,  225 ;  Formation  of  cavities,  231 ;  Precipitation  of  metals 
from  solution,  232 ;  Replacement  or  metasomatism,  233 ;  Concen- 
tration by  eruptive  after-action  or  pneumatolysis,  234 ;  Other 
causes  of  precipitation,  235 ;  Forms  of  ore  bodies,  236 ;  Fissure 
veins,  236  ;  Other  forms  of  ore  deposits,  241 ;  Secondary  changes 
in  ore  deposits,  242 ;  Weathering  or  superficial  alteration,  242 ; 
Secondary  deposition  below  water  level,  244 ;  Value  of  ores,  245 ; 
Classification  of  ore  deposits,  246  ;  References  on  ore  deposits,  249. 


CHAPTER  XIV 

IRON 251-277 

Ores  of  iron,  251 ;  Magnetite,  254  ;  Distribution  of  magnetites  in 
the  United  States,  264;  Non-titaniferous  magnetites,  264;  Other 
occurrences,  254  ;  Titaniferous  magnetites,  267  ;  Magnetite  sands, 
258  ;  Hematite,  259  ;  Distribution  of  hematite  ores  in  the  United 
States,  259 ;  Lake  Superior  region,  259 ;  Clinton  ore,  266 ;  Other 


CONTENTS 


PAOH 

hematite  occurrences,  268  ;  Limonite,  269  ;  Bog  ores,  269  ;  Residual 
limonites,  270  ;  Other  occurrences,  271 ;  Siderite,  272  ;  Production 
of  iron  ores,  273 ;  References  on  iron  ores,  276. 


CHAPTER  XV 

COPPER 278-302 

Ores,  278  ;  Impurities  in  copper  ores,  280  ;  Superficial  alteration 
of  copper  ores,  280;  Distribution  of  copper  ores  in  the  United 
States,  281  ;  Montana,  282 ;  Michigan,  287 ;  Arizona,  290 ;  Bisbee 
or  Warren  district,  290 ;  Jerome  district,.  292  ;  Clifton  district,  293  ; 
Globe  district,  294 ;  Appalachian  region,  294 ;  Utah,  296 ;  Call- 
fornia,  297  ;  Other  occurrences,  298 ;  Uses  of  copper,  298  ;  Produc- 
tion of  copper,  299  ;  References  on  copper,  301. 


CHAPTER  XVI 

LEAD  AND  ZINC 303-324 

Ores  of  lead,  303 ;  Ores  of  zinc,  303 ;  Superficial  alteration  of 
lead  and  zinc  ores,  305 ;  Distribution  of  lead  and  zinc  ores  in  the 
United  States,  305  ;  Lead  alone,  306  ;  Appalachian  belt,  306  ;  South- 
eastern Missouri,  306  ;  Desilverized  lead,  307  ;  Zinc  ores  alone, 
307  ;  Eastern  and  southern  states,  308 ;  Sussex  County,  N.  J.,  308  ; 
Virginia  and  Tennessee,  310 ;  Pennsylvania,  311 ;  Lead  and  zinc 
ores  of  the  Mississippi  Valley  region,  311 ;  Upper  Mississippi  Valley 
area,  311 ;  Ozark  region,  314 ;  Origin  of  the  ores,  316 ;  Rocky 
Mountain  states,  318 ;  Uses  of  lead  and  zinc,  319 ;  Uses  of  lead, 
319 ;  Uses  of  zinc,  320  ;  Production  of  lead  and  zinc,  321 ;  Refer- 
ences on  lead  and  zinc,  323. 


CHAPTER  XVII 

GOLD  AND  SILVER 325-363 

Ores  of  gold,  325  ;  Ores  of  silver,  325  ;  Mode  of  occurrence,  326  ; 
Weathering  and  secondary  enrichment,  327 ;  Classification,  327 ; 
Geological  distribution,  329  ;  Extraction,  329 ;  Distribution  of  gold 
and  silver  ores,  331  ;  Cordilleran  region,  332 ;  Pacific  coast  Creta- 
ceous gold-quartz  ores,  332 ;  Mother  Lode  belt,  333 ;  Nevada 
County,  334 ;  Central  belt  of  gold-silver  ores,  335 ;  Mercur,  Utah, 
336  ;  Other  occurrences,  337  ;  Eastern  belt  of  Tertiary  gold-silver 
veins,  337 ;  Cripple  Creek,  338 ;  San  Juan  region,  341 ;  Tonopah, 
Nev.,  343;  Comstock  Lode,  Nev.,  344;  Other  occurrences,  345; 
Auriferous  gravels,  346  ;  Black  Hills  region,  350  ;  Homestake  belt, 


CONTENTS  XV 

PAGE 

351  ;  Siliceous  Cambrian  ores,  352  ;  Michigan  region,  352  ;  Eastern 
crystalline  belt,  352  ;  Alaska,  353;  Uses  of  gold,  357  ;  Uses  of  silver, 
358 ;  Production  of  gold  and  silver,  358 ;  References  on  gold  and 
silver,  360. 


CHAPTER 

SILVER-LEAD 364-374 

Silver-lead  ores,  364  ;  Lead ville  District,  Colo.,  364  ;  Aspen,  Colo., 
367  ;  Other  occurrences,  369  ;  Park  City,  Utah,  370 ;  Tintic  District, 
Utah,  372  ;  Cceur  d'Alene,  Ido.,  372 ;  Montana,  Nevada,  etc.,  373 ; 
References  on  silver-lead  ores,  374. 

CHAPTER  XIX 

ALUMINUM,  MANGANESE,  AND  MERCURY 375-395 

Ores  of  aluminum,  375 ;  Distribution  of  bauxite  in  the  United 
States,  376  ;  Georgia-Alabama,  377  ;  Arkansas,  378  ;  New  Mexico, 
379 ;  Uses  of  aluminum,  379 ;  Uses  of  bauxite,  380 ;  Production 
of  bauxite  and  aluminum,  380 ;  References  on  bauxite  and  alumi- 
num, 383 ;  Manganese,  383 ;  Manganese  ores,  383 ;  Origin,  384 ; 
Distribution  of  manganese  ores  in  the  United  States,  384  ;  Eastern 
area,  385 ;  Arkansas,  387  ;  Other  United  States  occurrences,  387 ; 
Uses  of  manganese,  388 ;  Production  of  manganese,  388 ;  Refer- 
ences on  manganese,  390 ;  Ores  of  mercury,  390 ;  Mode  of  occur- 
rence, 390  ;  Distribution  in  the  United  States,  390 ;  California,  391 ; 
Texas,  392  ;  Origin,  393 ;  Uses  of  mercury,  393 ;  Production  of 
mercury,  394  ;  References  on  mercury,  396. 


CHAPTER  XX 

MINOR  METALS 396-417 

Ores  of  antimony,  396  ;  Distribution  of  antimony  in  the  United 
States,  396 ;  Uses,  397  ;  Production  of  antimony,  397  j  References 
on  antimony,  397  ;  Arsenic,  398  ;  References  on  arsenic,  398  ;  Bis- 
muth, 399;  Ores,  399;  Distribution,  399;  Uses  and  production, 
399  ;  Ores  of  chromic  iron,  399  ;  Origin  of  chromite,  400  ;  Analyses, 
400 ;  Distribution  of  chromic  iron  in  United  States,  400  ;  Uses,  401 ; 
Production  of  chromite,  402  ;  References  on  chromic  iron  ore,  402  ; 
Molybdenum,  ores  and  occurrences,  403 ;  Uses  of  molybdenum, 
403  ;  Production  of  molybdenum,  403  ;  References  on  molybdenum, 
403 ;  Nickel  and  cobalt,  403  ;  Ores,  403  ;  Distribution,  404;  Eastern 
occurrences  of  nickel,  404 ;  Other  occurrences,  405  ;  Uses  of  nickel, 
405 ;  Uses  of  cobalt,  406  ;  Production,  406 ;  References  on  nickel 


Xvi  CONTENTS 

and  cobalt,  407;  Platinum  group  of  metals,  407;  Platinum,  407; 
Distribution  in  the  United  States,  407  ;  Uses  of  platinum,  408  ;  Pro- 
duction of  platinum,  408  ;  References  on  platinum,  409  ;  Palladium, 
409  ;  Osmium,  409  ;  Iridium,  410  ;  Tin,  410  ;  Ores,  410  ;  Mode  of 
occurrence,  410;  Distribution  in  the  United  States,  411;  Uses  of 
tin,  412;  Production  of  tin,  412 ;  References  on  tin,  413  ;  Titanium, 
413;  Ores,  413;  Occurrence,  413;  Uses,  414;  References  on  tita- 
nium, 414  ;  Tungsten,  414  ;  Ores,  414;  Occurrence,  415  ;  Uses,  416  ; 
Production,  415  ;  References  on  tungsten,  416  ;  Uranium  and  vana- 
dium, 416  ;  Ores,  416  ;  Uses,  416 ;  Production,  416 ;  References  on 
uranium  and  vanadium,  417. 


APPENDIX  I 
STATISTICS  OF  PRODUCTION  FOR  1905 419-428 

APPENDIX  II 

BIBLIOGRAPHY  OF  IMPORTANT  PAPERS  PUBLISHED  SINCE  APPEARANCE 

OF  FIRST  EDITION 429-434 


LIST   OF  ILLUSTRATIONS 

FIG.  PAGE 

1.  Diagram  showing  changes  occurring  in  passage  of  vegetable  tissue 

to  graphite 13 

2.  Section  in  coal  measures  of  western  Pennsylvania,  showing  fire 

clay  under  coal  beds 16 

3.  Section  showing  irregularities  in  coal  seam,    a,  split ;  6,  parting  of 

shale  ;   c,  pinch  ;   d,  swell ;   e,  cut  out 17 

4.  Section  of  faulted  coal  seam 17 

6.    Section  across  Coosa,  Ala.,  coal  field,  showing  folding  and  faulting 

characteristic  of  southern  end  of  Appalachian  coal  field    .        .  20 

6.  Map  of  Pennsylvania  anthracite  field 23 

7.  Sections  in  Pennsylvania  anthracite  field 24 

8.  Coal  breaker  in  Pennsylvania  anthracite  region       ....  25 

9.  Section  across  Eastern  Interior  coal  field          .        .  .        ,26 

10.  Shaft  house  and  tipple,  bituminous  coal  mine,  Spring  Valley,  HI.    .  27 

11.  Generalized  section  of  Northern  Interior  coal  field  .        ...  28 

12.  Composite  section  showing  structure  of  lower  coal  measures  in  Iowa  29 

13.  Section  of  anticlinal  fold  showing  accumulation  of  gas,  oil,  and 

water 43 

14.  Map  showing  oil  and  gas  fields  of  United  States       ....  49 

15.  Geological  section  in  Ohio-Indiana  oil  and  gas  field         ...  60 

16.  Section  of  Spindle  Top  oil  field  near  Beaumont,  Tex.      ...  51 

17.  Section  in  Los  Angeles  oil  field 63 

18.  Map  of  asphalt  and  bituminous  rock  deposits  of  United  States       .  68 

19.  Section  of  Gilsonite  vein,  Utah 69 

20.  Map  showing  distribution  of  crystalline  rocks  (mainly  granite)  in 

United  States 76 

21.  Map  showing  marble  areas  of  eastern  United  States        ...  81 

22.  Section  showing  cleavage  and  bedding  in  slate        ....  87 

23.  Section  in  slate  quarry  with  cleavage  parallel  to  bedding,     a,  purple 

slate ;    6,  unworked ;    c  and  d,  variegated ;   e  and  /,  green ; 

g  and  A,  gray  green  ;  i,  quartzite  ;  j,  gray  with  black  patches  .  88 

24.  Section  showing  formation  of  residual  clay 93 

25.  Section  of  a  sedimentary  clay  deposit 93 

26.  Map  showing  distribution  of  salt-producing  areas  in  United  States, 

compiled  from  various  geological  survey  reports       .        .        .  128 

27.  Map  showing  gypsum-producing  localities  of  United  States    .        .  141 

28.  Map  of  Florida  phosphate  deposits 148 

29.  Map  of  Tennessee  phosphate  areas 161 

xvii 


Xviii  LIST   OF   ILLUSTRATIONS 


30.  Vertical  section  showing  geologic  position  of  Tennessee  phosphates    152 

31.  Map  showing  distribution  of  abrasives  in  United  States  .         .        .169 

32.  Section  showing  occurrence  of  corundum  around  border  of  dunite 

mass 164 

33.  Asbestos  vein  in  serpentine 168 

34.  Ideal  section  across  a  river  valley,  showing  the  position  of  ground 

water  and  the  undulations  of  the  water  table  with  reference  to 

the  surface  of  the  ground  and  bed  rock 208 

36.   Geologic  section  of  Atlantic  Coastal  Plain,  showing  water-bearing 

horizons 210 

36.  Section  from  Black  Hills  across  South  Dakota,  showing  artesian 

well  conditions 211 

37.  Replacement  vein  in  syenite  rock,  War  Eagle  mine,  Rossland,  B.C. 

a,  granular  orthoclase  with  a  little  sericite  ;  6,  secondary  biotite  ; 

q,  secondary  quartz  ;  c,  chlorite ;  black,  secondary  pyrrhotite    234 

38.  Section  of  vein  in  Enterprise  mine,  Rico,  Colo.      The  right  side 

shows  later  banding  due  to  reopening  of  the  fissure  .        .        .237 

39.  Section  showing  change  in  character  of  vein  passing  from  gneiss  (g} 

to  quartz  porphyry  Qj) 238 

40.  Tabulation  of  strikes  of  principal  veins  in  Monte  Cristo,  Wash., 

district 239 

41.  Linked  veins 240 

42.  Gash  vein  with  associated  "flats"  and  "pitches"  —  Wisconsin 

zinc  region 240 

43.  Section  at  Bonne  Terre,  Mo.,  showing  ore  disseminated  through 

limestone 241 

44.  Section  through  Copper  Queen  mine,  Bisbee,  Ariz.,  showing  varia- 

ble depth  of  weathering     243 

45.  Map  showing  distribution  of  iron  ores  in  United  States  .        .        .    253 

46.  Map  of  Lake  Superior  iron  regions,  shipping  ports,  and  transporta- 

tion lines   259 

47.  Sections  of  iron  ore  deposits  in  Marquette  range      ....     260 

48.  Generalized  vertical  section  through  Penokee-Gogebic  ore  deposit 

and  adjacent  rocks,  Colby  mine,  Bessemer,  Mich.    .        .        .261 

49.  Generalized  vertical  section  through  Mesabi  ore  deposit  and  adja- 

cent rocks          .        .        .        . 262 

50.  Section  of  Clinton  ore  beds,  Oxmoor,  Ala.     a,  red  sandstone,  6' ; 

6,  yellow  sandstone,  6' ;    c,  red  sandstone,  16' ;    d,  ore,  22', 
upper  2'  soft;  e,  shale,  6' ;  /,  rich  ore,  2'  6"     .        .        .        .     266 

51.  Section  illustrating  formation  of  residual  limonite  in  limestone       .    270 

52.  Map  showing  distribution  of  copper  ores  in  United  States       .        .     282 
63.    Map  of  Butte,  Mont.,  district,  showing  distribution  of  veins  and 

geology 283 

54.   Section  at  Butte,  Mont.,  showing  mode  of  occurrence  of  the  ore     .    284 


LIST   OF   ILLUSTRATIONS  XIX 

FIG.  FAGK 

55.  Section  across  Keweenaw  Point 287 

56.  Section  showing  occurrence  of  amygdaloidal  copper,  Quincy  mine, 

Michigan 288 

57.  Geological  section  at  Bisbee,  Ariz 291 

58.  Generalized  section  of  ore  bodies  at  Bisbee,  Ariz 292 

59.  Section  of  Morenci  district.     P,  porphyry  ;  S,  unaltered  sediments  ; 

F,  fissure  veins ;    M,  metamorphosed  limestone  and  shale ; 

O,  contact  metamorphic  ores ;  R,  disseminated  chalcocite        .  293 

60.  Section  of  ore  body  at  Bully  Hill,  Calif 298 

61.  Map  showing  distribution  of  lead  and  zinc  ores  in  United  States     .  305 

62.  Generalized  section  of  southeastern  Missouri  lead  region         .        .  306 
6.3.    Model  of  Franklin  zinc-ore  body 309 

64.  Section  of  Bertha  zinc  mines,  Wythe  County,  Va.,  showing  irregu- 

lar surface  of  limestone  covered  by  residual  clay  bearing  ore    .    310 

65.  Section  showing  occurrence  of  lead  and  zinc  ores  in  Wisconsin, 

with  fissure  ore  in  flats  and  pitches,  and  disseminated  ore  in 

oil  rock 312 

66.  Map  of  Ozark  region 314 

67.  Generalized  section  showing  occurrence  of  lead  and  zinc  ore  in 

southwestern  Missouri 316 

68.  A  typical  hoisting  outfit  in  the  southwestern  Missouri  zinc  region  .  316 

69.  Map  showing  distribution  of  gold  and  silver  ores  in  United  States  .  331 

70.  Map  and  section  of  portion  of  Mother  Lode  district,  Calif.     Pgv, 

river  gravels,  usually  auriferous ;  Ng,  auriferous  river  gravels. 
Sedimentary  rocks  :  Jm,  mariposa  formation  (clay,  slate,  sand- 
stone, and  conglomerate)  ;  <?c,  calaveras  formation  (slaty 
mica  schists) .  Igneous  rocks :  Nl,  latite  ;  Nat,  andesite  tuffs, 
breccia,  and  conglomerate  ;  mdi,  meta-diorite ;  Sp,  serpentine  ; 
,  ma,  meta-andesite ;  cms,  amphibole  schist  ....  334 

71.  Section  illustrating  relations  of  auriferous  quartz  veins  at  Nevada 

City,  Calif 335 

72.  Section  at  Mercur,  Utah 336 

73.  Map  of  Colorado  showing  location  of  mining  regions       .        .        .  338 

74.  Section  of  vein  at  Cripple  Creek,  Colo 339 

75.  Geologic  map  of  Telluride  district,  Colorado,  showing  outcrop  of 

more  important  veins 342 

76.  Ideal  cross  section  of  rocks  at  Tonopah,  Nev 343 

77.  Section  of  Comstock  Lode.     D,  diorite  ;  Q,  quartz  ;  V,  vein  matter 

in  earlier  diabase   (Db)  ;    H,   earlier   hornblende   andesite ; 

A,  augite  andesite 344 

78.  Generalized  section  of  old  placer,  with  technical  terms,     a,  volcanic 

cap ;  6,  upper  lead  ;  c,  bench  gravel ;  d,  channel  gravel  .        .     347 

79.  Section  of  Homestake  Belt  at  Lead,  S.D.,  showing  relation  of 

ancient  and  modern  placers  to  Homestake  Lode       .        .        .    350 


XX  LIST  OF  ILLUSTRATIONS 

FIG.  PACK 

80.  Typical  section  of  siliceous  gold  ores,  Black  Hills,  S.D.  .        .        .  351 

81.  Map  showing  mineral  deposits  of  Alaska  as  far  as  known        .        .  354 

82.  Sketch  map  of  Douglas  Island,  Alaska 355 

83.  Cross  section  through  Alaska  Treadwell  mine  on  northern  side  of 

Douglas  Island 356 

84.  Ideal  section  across  Leadville  district 366 

85.  Section  of  ore  body  at  Aspen,  Colo 368 

86.  Diagrammatic  section  across  a  northeasterly  lode  at  Rico,  Colo., 

showing  "  blanket "  of  ore 369 

87.  Vein  filling  a  fault  fissure,  Enterprise  mine,  Rico,  Colo.          .        .  370 

88.  Section  of  lead-silver  vein,  Cceur  d'Alene,  Ido 373 

89.  Geologic  map  of  Alabama-Georgia  bauxite  region    .        .        .        .377 

90.  Section  of  bauxite  deposit,     a,  Residual  mantle  ;  &,  Red  sandy  clay 

soil;    c,  Pisolitic  ore;    d,  Bauxite  with  clay;    e,  Clay  with 

bauxite  ;  /,  Talus ;  gr,  Mottled  clay  ;  h,  Drainage  ditch    .        .  378 

91.  Map  showing  Georgia  manganese  areas 385 

92.  Section  in  Georgia  manganese  area  showing  geologic  relations  of 

manganese,  limonite,  and  ocher 386 

93.  Section  of  Batesville,  Ark.,  manganese  region,  illustrating  geological 

structure  and  relation  of  different  formations  to  marketable 

and  non-marketable  ore 387 

94.  Map  of  California  mercury  localities 391 

95.  Map  showing  Texas  mercury  region 392 

96.  Section  of  cinnabar  vein  in  limestone,  Terlingua,  Tex.    .        .        .393 

97.  Sketch  map  showing  location  of  Carolina  tin  belt    ....  411 


PLATES 

PLATE  PAGE 

I.     Map  showing  distribution  of  coal  in  United  States.  Frontispiece 
II.     Fig.  1.    Pit  working  (stripping)  near  Milnesville,  Pa.      The 

mammoth  seam  is  uncovered  in  bottom  of  pit    .        .        .      31 
Fig.  2.  Lignite  seam,  Williston,  N.D 31 

III.  Fig.  1.   General  view  of  Tuna  Valley,  in  Pennsylvania  oil  field      48 
Fig.  2.    View  in  Los  Angeles,  Calif. ,  oil  field.    Such  close  spac- 
ing of  oil  derricks  tends  to  hasten  the  exhaustion  of  the 

oil  supply 48 

IV.  General  view  of  Spindle  Top  oil  field,  Beaumont,  Tex.    .        .      51 
V.     Fig.  1.    Quarry  of  bituminous  sandstone,  Santa  Cruz,  Calif.    .      60 

Fig.  2.   Granite  quarry,  Hard  wick,  Vt 60 

VI.     Quarry  in  limestone,  Bedford,  Ind. 80 

VII.     Marble  quarry,  Proctor,  Vt 82 

VIII.     View  of  green  slate  quarry,  Pawlet,  Vt 88 

IX.     Bank  of  sedimentary  clay,  Woodbridge,  N.J.     This  section 

affords  at  least  five  kinds  of  clay 103 

X.     Fig.  1.    Quarry  of  natural  cement  rock,  Cumberland,  Md.      .     117 
Fig.  2.   Marl  pit  at  Warners,  N.Y.     The  dark  streaks  are 

peat  and  the  marl  is  underlain  by  clay       .        .        .        .117 
XI.    Fig.  1.   Interior  view  of  salt  mine,  Livonia,  N.Y.    .        .        .129 

Fig.  2.   Borax  mine  near  Daggett,  Calif 129 

XII.  Fig.  1.  Gypsum  quarry,  Alabaster,  Mich.  Shows  gypsum 
overlain  by  glacial  drift.  The  dump  in  foreground  is  over- 
burden removed  from  gypsum 139 

Fig.  2.   Eock  phosphate  mine  near  Ocala,  Fla.        .        .        .139 

XIII.  Fig.  1.    Grindstone  quarry,  Tippecanoe,  Ohio .        .        .        .159 
Fig.  2.   Corundum  vein  between  peridotite  and  gneiss,  Corun- 
dum Hill,  Ga 159 

XIV.  Fig.  1.   View  of  open  cut  in  magnetite  deposit,  Mineville,  N.Y. 

The  pillars  are  ore  left  standing  to  support  the  gneiss 

hanging  wall 254 

Fig.  2.   General  view  of  magnetic  separating  plants  and  shaft 

houses,  Mineville,  N.Y 254 

XV.    Fig.  1.   Iron  mine,  Soudan,  Minn.     Shows  old  open  pit  with 

jasper  horse  in  middle 261 

Fig.  2.   Outcrop  of  Clinton  iron  ore,   Red  Mountain,  near 

Birmingham,  Ala 261 


Xxii  PLATES 

PLATE  1'AGB 

XVL     General  view  of  Mountain  Iron  mine,  Mesabi  Eange,  Minn. 
Shows  mining  of  ore  with  steam  shovels  and  covering 

of  (a)  glacial  drift 264 

XVIL     Fig.  1.    Pit  of  residual  limonite,  Shelby,  Ala 270 

Fig.  2.  Old  limonite  mine,  Ivanhoe,  Va.,  showing  pinnacled 
surface  of  limestone  which  underlies  the  ore-bearing  clay. 
The  level  of  surface  before  mining  began  is  seen  on  either 

side  of  excavation 270 

XVIII.     Anaconda  group  of  mines,  Butte,  Mont 285 

XIX.     Fig.  1.   Smelter  of  Clifton  Copper  Co.,  Clifton,  Ariz.       .        .     293 

Fig.  '2.   View  of  Bingham  Canon,  Utah 293 

XX.     Fig.  1.    Kennedy  mine  on  the  Mother  Lode  near  Jackson, 

Calif 333 

Fig.  2.    Auriferous  quartz  veins  in  Maryland  mine,  Nevada 

City,  Calif 333 

XXI.     Fig.  1.    View  of  Independence  mine  and  Battle  Mountain, 

Cripple  Creek,  Colo 340 

Fig.  2.    General  view  of  region  around  Tonopah,  Nev.     .        .     340 
XXII.     Fig.  1.    Hydraulic  mining  of  auriferous  gravel.     The  sluice 

box  in  foreground  is  for  catching  the  gold  ....     348 
Fig.  2.  An  Alaskan  placer  deposit 348 

XXIII.  Homestake  mills,  hoists  and  open  cuts  at  Lead,  S.D.     .        .     351 

XXIV.  Fig.  1.   General  view  of  Kico,  Colo.,  and  Enterprise  group  of 


Fig.  2.   Ontario  mine,  Park  City,  Utah    .        .  .        .369 

XXV.     Fig.  1.   Bauxite  bank,  Eock  Kun,  Ala.    .  .        .        .376 

Fig.  2.   Furnace  for  roasting  mercury  ore,  Terlingua,  Tex.     .    376 


ABBREVIATIONS   USED 

In  the  references  at  the  end  of  each  chapter,  the  volume  numbers  are  given 

in  Roman  numerals.      Numbers  following  a  :  indicate  page  numbers. 

The  date  of  publication  follows  these,  and  is  separated  from  them  by  a 

comma. 
Ala.  Ind.  and  Sci.  Soc.,  Proc.  —  Alabama  Industrial  and  Scientific  Society, 

Proceedings. 

Amer.  Geol.  —  American  Geologist. 
Amer.  Inst.  Min.  Eng.,    Trans. — American   Institute  Mining  Engineers, 

Transactions. 

Amer.  Jour.  Sci  — American  Journal  of  Science. 
Col.  Sci.  Soc.,  Proc.  —  Colorado  Scientific  Society,  Proceedings. 
Eng.  and  Min.  Jour.  —  Engineering  and  Mining  Journal. 
Geol.  Soc.  Amer.,  Bull.  —  Geological  Society  of  America,  Bulletin. 
Jour.  Geol.  —  Journal  of  Geology. 
Min.  and  Met.  —  Mining  and  Metallurgy. 
Min.  and  Sci.  P.  —  Mining  and  Scientific  Press. 
Min.  Indus.  —  Mineral  Industry. 
Min.  Mag.  —  Mining  Magazine. 
Mo.  Geol.  Surv.  — Missouri  Geological  Survey. 

N.  T.  Acad.  Sci.,  Trans.  — New  York  Academy  of  Science,  Transactions. 
N.  Ca.  Geol.  Surv.—  North  Carolina  Geological  Survey. 
Sch.  M.  Quart.  —  School  of  Mines  Quarterly. 

U.  S.  Geol.  Surv.,  Mon.  —United  States  Geological  Survey,  Monograph. 
U.  S.  Geol.  Surv.,  Ann.  Sept.—  United  States  Geological  Survey,  Annual 

Report. 
Zeitsch.  f.  Prak.  Geol.  —  Zeitschrift  fur  Praktische  Geologie. 


xxiii 


PART   I 
NON-METALLIC  MINERALS 


CHAPTER  I 
COAL 

Kinds  of  Coal.  —  There  is  such  an  intimate  gradation  be- 
tween vegetable  accumulation  now  in  process  of  formation 
and  mineral  coal  that  it  is  generally  admitted  that  coal  is  of 
vegetable  origin.  By  a  series  of  slow  changes  (p.  12),  the 
vegetable  remains  lose  water  and  gases,  the  carbon  becomes 
concentrated,  and  the  materials  assume  the  mineralized  ap- 
pearance of  coal.  To  the  stages  of  this  process  names  are 
given,  four  of  which  —  peat,  lignite,  bituminous  coal,  and 
anthracite  coal  —  are  commonly  known. 

Peat  (79-83). — This,  which  may  represent  the  first  stage 
in  coal  formation,  is  formed  chiefly  by  the  growth  of 
the  bog  moss,  sphagnum,  in  moist  places.  A  section  in  a 
peat  bog,  from  the  top  downward,  shows  :  (1)  a  layer 
of  living  moss,  and  other  plants ;  (2)  a  layer  of  dead 
moss  fibers,  whose  structure  is  clearly  recognizable,  and 
which  grades  into  (3)  a  layer  of  fully  formed  peat,  a 
dense  brownish  black  mass,  in  which  the  vegetable  struc- 
ture is  often  indistinct. 

The  following  analyses  show  the  difference  in  composition 
of  the  different  layers.  They  also  show  that  while  during 
this  change  the  hydrogen  and  oxygen  diminish,  the  carbon 
increases  in  proportion. 

3 


ECONOMIC   GEOLOGY   OF   THE   UNITED   STATES 


MATERIAL 

CARBON 

HYDROGEN 

OXYGEN 

NITROGEN 

49  88 

6  54 

4242 

1  16 

Porous,  light  brown  sphag- 

50.86 

5.8 

42.57 

.77 

Porous,  red  brown  peat   .    . 

53.51 

5.9 

40.59 

Heavy  brown  peat  .... 

56.43 

5.32 

38.25 

Heavy  black  peat    .... 

59.7 

5.7 

33.04 

1.56 

Lignite.  —  This  substance,  also  called  brown  coal,  repre- 
senting the  second  stage  in  coal  formation,  is  brownish  black 
or  black  in  color,  and  often  shows  a  brilliant  luster,  conchoidal 
fracture,  and  brown  streak.  Where  the  lumps  have  formed 
from  trunks  or  other  large,  woody  masses,  the  vegetable 
structure  is  often  clearly  visible.  It  burns  readily,  but  with 
a  long,  smoky  flame,  and  hence  with  lower  heating  power 
than  the  true  coal.  Because  of  the  large  amount  of  mois- 
ture, it  often  dries  out  on  exposure  to  the  air,  and  rapidly 
disintegrates  to  a  powdery  mass. 

The  lignites  have  been  found  in  the  more  recent  geological  periods. 
Because  of  the  greater  age  and  the  greater  compression  of  the  vegetable 
matter,  due  to  the  pressure  of  overlying  strata,  lignite  resembles  true 
coal  more  closely  than  peat.  In  fact,  in  favorable  situations,  the  altera- 
tion of  Tertiary  and  Cretaceous  coals  has  proceeded  as  far  as  to  trans- 
form them  beyond  the  stage  of  lignite. 

Jet  is  a  coal-black  variety  of  lignite,  with  resinous  luster  and  sufficient 
density  to  permit  its  being  carved  into  small  ornaments.  It  is  obtained 
on  the  Yorkshire  coast  of  England,  where  a  single  seam  produced  5180 
pounds,  valued  at  $1250.  According  to  Phillips,  jet  is  simply  a  conif- 
erous wood,  still  showing  the  characteristic  structure  under  the  micro- 
scope. ("  Geology  of  England  and  Wales,"  p.  278.) 

Bituminous  Coal.  —  This  represents  the  third  stage  in  coal 
formation.  It  is  denser  than  lignite,  deep  black,  compara- 


COAL  5 

tively  brittle,  and  breaks  with  cubical,  or  sometimes  con- 
choidal,  fracture.  On  superficial  inspection  it  usually  shows 
no  trace  of  vegetable  remains ;  but  in  thin  sections  examined 
under  the  microscope,  traces  of  woody  fiber,  lycopod  spores, 
etc.,  are  commonly  seen.  Bituminous  coal  burns  readily, 
with  a  smoky  flame  of  yellow  color,  but  with  much  greater 
heating  power  than  lignite.  It  does  not  disintegrate  on  ex- 
posure to  air  as  readily  as  lignite  does.  Most  bituminous 
coal  is  of  earlier  age  than  lignite ;  but  where  the  two  occur 
in  the  same  formation,  as  in  parts  of  the  West,  the  lignite 
is  commonly  in  horizontal  strata,  while  the  bituminous  coal 
occurs  in  areas  of  at  least  slight  disturbance. 

When  freed  of  their  volatile  hydrocarbons  and  other  gaseous  constitu- 
ents by  heating  to  redness  in  an  oven,  many  bituminous  coals  cake  to  a 
hard  mass  called  coke.  Since  some  bituminous  coals  do  not  possess  this 
characteristic,  it  is  customary  to  divide  these  coals  into  coking  and  non- 
coking  coals. 

Cannel  coal  is  a  compact  variety  of  non-coking  bituminous 
coal  with  a  dull  luster  and  conchoidal  fracture.  Owing  to 
its  unusually  high  percentage  of  volatile  hydrocarbons,  upon 
which  its  chief  value  depends,  cannel  coal  ignites  easily, 
burning  with  a  yellow  flame.  (See  analysis  No.  14.) 

Semi-bituminous  is  a  name  applied  to  certain  varieties  in- 
termediate between  bituminous  and  anthracite  coal. 

Anthracite  Coal.  —  This  coal  is  black,  hard,  and  brittle, 
with  high  luster  and  conchoidal  fracture.  It  represents  the 
last  stage  in  the  formation  of  coal,  and  shows  no  traces 
of  vegetable  structure  within  its  mass,  although  plant 
impressions  are  often  abundant  in  the  rocks  immediately 
above  and  below  it.  Anthracite  has  a  lower  percentage 
of  volatile  hydrocarbons  and  higher  percentage  of  fixed 


6 


ECONOMIC  GEOLOGY  OF  THE  UNITED  STATES 


carbons  than  any  of  the  other  varieties  (p.  8).  On  this 
account,  it  ignites  much  less  easily  and  burns  with  a  short 
flame,  but  gives  great  heat. 

The  geological  distribution  of  anthracite  is  more  restricted 
than  that  of  bituminous  coal  and,  in  fact,  its  occurrence 
is  often  more  or  less  intimately  connected  with  dynamic 
disturbances. 

Proximate  Analysis  of  Coal.  —  An  elementary  analysis  of 
coal  (see  p.  14)  is  of  comparatively  little  practical  value. 
Therefore  proximate  analyses  are  commonly  employed,  in 
which  the  probable  method  of  combination  of  the  elements 
is  given.  By  the  proximate  method  the  elements  in  the 
coal  are  grouped  as  moisture,  volatile  hydrocarbons,  fixed 
carbon,  ash,  and  sulphur. 

The  following  table  gives  the  proximate  analysis  of  a 
number  of  coals  from  all  parts  of  the  United  States.  The 
analyses  are  arranged  in  the  following  order:  Peat,  Lignite, 
Bituminous  Coal,  Anthracite. 

PROXIMATE  ANALYSES  OF  COAL 


LOCALITY 

Moisture 

Volatile 
Hydro- 
carbon 

Fixed 
Carbon 

Ash 

Sulph. 

Fuel 
Ratio 

1.  Peat   

20.22 

52.31 

24.52 

.47 

Dismal  Swamp 

2.   Newcastle    .... 

13.69 

32.31 

48.32 

5.78 

.164 

1.49 

Washington 

3.    Kootznaboo      .     .     . 

2.41 

44.75 

47.93 

4.88 

.67 

1.07 

Alaska 

4.  Rockdale     .... 

33.63 

46.78 

7.45 

12.14 

.99 

.15 

Texas 

5.   Lignite        .... 

22.95 

23.64 

43.31 

5.10 

1.51 

S.  Platte  field,  Col. 

6.  Lignite    .    . 

21.11 

28  55 

44  98 

5  01 

1.58 

E.  field,  Montana 

COAL 


LOCALITY 

Moisture 

Volatile 
Hydro- 
carbon 

Fixed 
Carbon 

Ash 

Snlph. 

Fuel 
Ratio 

7    Lignite 

10.80 

43.10 

38.57 

7.53 

.87 

Corral  Hollow,  Cal. 

8.   Brookville  Coal    .     . 

1.47 

17.93 

75.508 

4.625 

.567 

4.21 

Conemaugh,    Cam- 

bric Co. 

9.   Pittsburg  Coal  .     .     . 

1.26 

31.79 

67.79 

7.16 

.79 

1.81 

Connelsville,   Fay- 

ette  Co. 

10.   Hocking  Valley  Coal 

5.93 

36.48 

62.41 

5.13 

1.09 

1.44 

Ohio 

11.    Warrior  

4.83 

18.95 

72.76 

3.28 

.17 

3.83 

Jeff.  Co.,  Ala. 

12    Jellico    .         .     . 

4.40 

31.56 

61.87 

1.86 

.31 

1.96 

Campbell  Co.,  Tenn. 

13.   Brazil  Block  Coal     . 

13.82 

35.16 

49.96 

1.06 

1.47 

1.42 

Brazil,  Ind. 

14.   Cannel  Coal     .     .     . 

1.47 

49.08 

26.35 

23.10 

1.48 

.53 

Cannelburg,  Ind. 

15.   Bituminous  Coal  .     . 

5.50 

39.50 

54.60 

5.40 

.  .  . 

1.38 

Belleville,  111. 

16    Butler          .... 

30.66 

54.94 

11.00 

2.544 

1.71 

Kentucky 

17.   Owasso  Coal  Comp'ny 

7.58 

35.70 

52.96 

3.76 

1.50 

1.48 

Owasso,  Mich. 

18.    Saginaw  Company    . 

5.82 

39.79 

45.15 

9.24 

3.83 

1.13 

Verne,  Mich. 

19.  Fort  Dodge      .     .     . 

7.48 

39.52 

45.54 

8.44 

5.28 

1.15 

Iowa 

20.   Lexington   .... 

9.24 

29.01 

42.19 

15.18 

4.38 

1.45 

Missouri 

21.    Hartshorne  Coal  .     . 

1.68 

41.00 

51.91 

5.41 

2.72 

1.26 

Hartshorne,  I.T. 

22.    Gwyn's  shaft  .     .     . 

.892 

14.57 

77.09 

6.24 

1.19 

5.28 

Sebastian  Co.,  Ark. 

23.    Semi-bituminous  .     . 

1.10 

il.27 

72.83 

12.04 

2.74 

6.46 

Johnson  Co.,  Ark. 

24    Coal  No  1 

.88 

31.57 

56.81 

8.93 

1.47 

1.79 

Thurber,  Texas 

25.  Coking  Coal     .    .    . 

.75 

31.13 

57.07 

11.05 

.  .  . 

1.80 

Raton  field,  Col. 

ECONOMIC   GEOLOGY   OF  THE   UNITED  STATES 


LOCALITY 

Moisture 

Volatile 
Hydro- 
carbon 

Fixed 
Carbon 

Ash 

Sulph. 

Fuel 
Ratio 

26.   Newcastle    .... 

7.992 

29.031 

63.806 

8.023 

1.148 

1.85 

Washington 

27.  Bituminous  Coal  .     . 

6.21 

31.32 

62.47 

11.10 

1.65 

Canyon  City,  Col. 

28.  Anthracite  .... 

1.58 

6.70 

87.46 

4.26 

.58 

13.05 

Crested  Butte,  Col. 

29.  Anthracite  .... 

2.90 

3.18 

88.91 

5.21 

. 

27.96 

Cerillos  field,  New 

Mexico 

30.  Mammoth    .... 

3.163 

3.717 

81.143 

11.078 

.899 

21.83 

W.  Middle  field,  Pa. 

31.  Mammoth    .... 

3.421 

4.381 

83.268 

8.203 

.727 

19.00 

N.  Middle  field,  Pa. 

The  moisture  can  be  driven  off  at  100°  C.  and  is  usually  highest  in 
peat  and  lignite;  the  volatile  hydrocarbons  are  the  easily  combustible 
elements,  and  decrease  toward  the  anthracitic  end  of  the  series;  the 
fixed  carbon  burns  with  difficulty  and  is  highest  in  the  anthracite 
coals.  The  ash  represents  noncombustible  mineral  matter  and  bears 
no  direct  relation  to  the  kind  of  coal ;  and  the  same  is  true  of  sulphur, 
which  is  present  as  an  ingredient  of  pyrite  or  gypsum. 

The  value  of  coal  for  fuel  or  other  purposes  is  determined  mainly 
by  the  relative  amounts  of  its  fuel  constituents,  viz.  the  volatile  hydro- 
carbons and  the  nonvolatile  or  fixed  carbons.  The  fuel  value,  or  fuel 
ratio,  is  determined  by  dividing  the  fixed  carbon  percentage  by  that 
of  the  volatile  hydrocarbons. 

The  fixed  carbon  represents  the  heating  element  of  the  coal,  while 
the  volatile  hydrocarbons  burn  easily,  but  have  little  heating  power. 
The  heating  power  and  fuel  ratio  will,  therefore,  increase  together. 
This  increase  in  the  heating  power  of  the  coal  is  only  true,  however, 
up  to  a  certain  point,  after  which  the  difficulty  in  making  the  coal 
burn  offsets  the  extra  amount  of  heat  developed.  Coals  with  a  high 
percentage  of  fixed  carbon  develop  great  heating  power,  while  those 
lower  in  fixed  carbon  and  high  in  volatile  hydrocarbons  lack  in  heating 
power,  but  are  free  burning. 


COAL 


9 


Moisture  is  a  nonessential  constituent  of  coal.  It  not  only  dis- 
places so  much  combustible  matter,  but  requires  heat  for  its  evapo- 
ration. Wheu  present  in  large  amounts  it  often  causes  the  coal  to 
disintegrate  while  drying  out.  It  ranges  from  1  per  cent  in  anthracite 
to  20  or  30  per  cent  in  lignites. 

Ash  also  displaces  combustible  matter,  but  otherwise  it  is  in  most 
cases  an  inert  impurity.  The  clinkering  of  coal  is  commonly  due  to 
a  high  percentage  of  fusible  impurities  in  the  ash,  and  for  metallur- 
gical work  the  composition  of  the  ash  often  has  to  be  considered. 

The  following  analyses  will  also  serve  to  illustrate  the  composition 

of  the  ash: — 

ASH  ANALYSES 


8iO, 

AltOs 

Fe,0, 

CaO 

MgO 
3.20 

MnO, 

SO, 

Alka- 
lies 

Chlo- 
rine 

P,08 

2.56 

Peat,  average  of 
several     .    .    . 

25.50 

5.78 

18.70 

24.00 

7.50 

1.72 

.60 

Lignite   .... 
Bituminous  Coal 

30.14 
34.32 

13.48 
14.62 

11.70 
22.94 

23.59 
14.85 

.88 
1.42 

3.32 
1.16 

14.22 
10.97 

Sulphur  is  an  objectionable  impurity  in  steaming  coals  on  account 
of  its  corrosive  action  on  the  boiler  tubes.  It  is  also  undesirable  in 
coals  to  be  used  for  metallurgical  purposes  and  gas  manufacture. 

Origin  of  Coal  (4). —  It  has  been  shown  that  there  are 
gradations  between  unquestioned  plant  beds  and  mineral 
coal,  and  that  coal,  besides  containing  the  same  materials 
as  plant  tissue,  often  shows  the  presence  of  plant  fibers, 
leaves,  stems,  seeds,  etc.  Moreover,  stumps  or  trunks  of 
trees  are  sometimes  found  standing  upright  in  the  coal, 
with  their  roots  penetrating  the  underlying  bed  of  clay  (5), 
just  as  trunks  of  trees  at  present  stand  in  bogs.  While 
these  facts  point  unmistakably  to  a  vegetable  origin  of 
coal,  it  is  less  easy  to  understand  the  exact  manner  in 
which  the  great  accumulations  of  vegetable  matter  have 
been  made,  and  the  changes  from  plant  tissue  to  mineral 


10  ECONOMIC   GEOLOGY   OP  THE   UNITED   STATES 

coal.  Each  of  these  points,  therefore,  demands  further 
consideration. 

Conditions  of  Vegetable  Accumulation  (4). — At  present 
there  are  several  conditions  under  which  plant  remains 
accumulate  to  considerable  depth  over  areas  in  some  cases 
of  large  size.  All  of  these  are  closely  associated  with 
water,  either  fresh  or  salt,  because  plant  remains  falling 
in  water  have  their  decay  so  retarded  by  the  exclusion  of 
air  that  accumulation  is  possible.  Of  these  the  following 
are  the  most  important :  (1)  accumulation  due  to  algae  on 
the  sea  bottom  beneath  a  sargasso  sea ;  (2)  marine  swamps, 
including  salt  marshes  and  mangrove  swamps;  (3)  delta 
deposits;  (4)  peat  bogs;  (5)  coastal  plain  marshes. 

While  accumulations  made  in  any  one  of  these  ways 
may  form  coal  beds,  and  while  individual  beds  may  be 
formed  which  are  due  to  any  of  these  causes,  to  many  of 
them  there  are  such  objections  as  to  render  them  extremely 
improbable  as  general  explanations  for  the  great  number 
of  widely  extended  deposits  of  coal.  The  theory  of  accumu- 
lation from  deposits  of  algse,  for  example,  demands  deep 
water  of  an  open  ocean  for  the  circulation  of  ocean  cur- 
rents. But  most  coal  beds  are  evidently  formed  either  on 
the  land  or  else  in  shallow  water  of  lakes,  lagoons,  or  sea- 
coast  swamps. 

To  the  theory  of  various  swamps  there  are  two  serious 
objections  :  (1)  that  in  such  deposits  as  are  now  forming, 
the  currents  are  bringing  more  fragmental  sediments  than 
are  commonly  present  in  coal  beds  ;  (2)  that  at  present 
only  one  kind  of  tree,  the  mangrove,  is  adapted  to  growth  in 
salt  water.  It  is,  of  course,  possible  that  in  earlier  ages  the 
number  of  trees  adapted  to  this  mode  of  life  was  far  greater. 


COAL  11 

Streams  are  bringing  plant  remains  to  lakes  or  oceans 
and  incorporating  them  in  their  deltas  ;  but  nowhere  are 
such  extensive  accumulations  now  forming  as  to  make  large 
coal  fields  in  this  manner.  Moreover,  the  amount  of  sedi- 
ment brought  in  such  places  would  seem  to  exclude  the 
possibility  of  the  deposit  of  large  areas  of  vegetable  mat- 
ter free  from  a  great  admixture  of  sediment.  The  combi- 
nation of  this  source  of  vegetable  supply  with  that  caused 
by  the  growth  of  marine  or  fresh-water  swamp  plants  in 
the  delta  lagoons  would  increase  the  chances  of  the  forma- 
tion of  coal  beds  by  this  means;  but  even  with  this  addi- 
tion, it  seems  impossible  to  accept  this  as  a  general  theory 
for  the  formation  of  extensive  beds  of  coal. 

It  is  a  well-known  fact  that  thick  deposits  of  vegetable 
matter,  often  covering  areas  of  several  square  miles,  are 
formed  in  the  peat  bogs  that  in  so  many  places  represent 
the  last  stage  of  lake  or  pond  filling  in  cool,  temperate 
climates.  Each  of  these  bogs  would,  under  favorable 
circumstances,  change  to  a  bed  of  coal,  and  some  of  them 
are  extensive  enough  to  form  coal  beds  of  large  size.  But 
such  bogs  are,  compared  to  our  larger  coal  fields,  far  too 
limited  in  area  to  admit  of  the  acceptance  of  this  explana- 
tion to  account  for  great  coal  fields  without  assuming  far 
more  widespread  bog-forming  conditions  than  any  at  present 
known. 

Perhaps  the  most  perfect  resemblance  to  coal-forming 
condition  is  that  now  found  on  such  coastal  plain  areas  as 
that  of  southern  Florida  and  the  Dismal  Swamp  of  Virginia, 
North  Carolina.  Both  of  these  areas  are  very  level,  though 
with  slight  depressions  in  which  there  is  either  standing 
water  or  swamp  conditions.  In  both  regions  there  is  such 


12  ECONOMIC   GEOLOGY   OF  THE    UNITED   STATES 

general  interference  with  free  drainage  that  there  are  exten- 
sive areas  of  swamp,  and  in  both  there  are  beds  of  vegetable 
accumulations.  In  each  of  these  areas  there  is  a  general 
absence  of  sediment  and  therefore  a  marked  variety  of  vege- 
table deposit.  If  either  of  these  areas  were  submerged  be- 
neath the  sea,  the  vegetable  remains  would  be  buried  and  a 
further  step  made  toward  the  formation  of  a  coal  bed.  Re- 
elevation,  making  a  coastal  plain,  would  permit  the  accumula- 
tion of  another  coal  bed  above  the  first,  and  this  process 
might  be  continued  again  and  again. 

In  support  of  the  theory  that  coal  was  accumulated  in 
some  such  situation  as  this,  are  a  number  of  facts  :  (1)  the 
coal  beds  occur  over  wide  areas  in  sediments  which  were 
deposited  near  land  borders  and  which  may  therefore  have 
been  again  and  again  raised  above  sea  level  to  form  extensive 
coastal  plains ;  (2)  there  are  evidences  of  land  conditions  re- 
vealed in  the  workings  of  some  mines ;  (3)  the  enormous 
area  of  some  coal  fields  call  for  some  such  widespread  condi- 
tions as  coastal  plains  might  provide ;  (4)  the  slight  admix- 
ture of  sediment  indicates  the  absence  of  conditions  of 
sediment  supply,  e.g.  rivers,  waves,  tidal  currents,  and  wind- 
formed  currents ;  (5)  vegetable  accumulations  made  in  such 
situations  would  require  but  slight  changes  in  land  level  to 
be  buried  beneath  sedimentary  strata  as  the  coal  beds  have 
been. 

Chemical  Changes  occurring  during  Coal  Formation.  — 
Dead  plant  tissue  when  exposed  to  the  air  oxidizes  rapidly 
and  decays,  all  of  the  gaseous  elements  passing  off,  leaving 
only  the  mineral  matter  which  the  plant  tissue  contained. 
The  exclusion  of  air  caused  by  the  presence  of  water,  as  in  a 
pond  or  a  swamp,  greatly  retards  oxidation ;  but,  as  it  slowly 


COAL 


13 


proceeds  the  oxygen,  nitrogen,  and  hydrogen  of  the  plant 
tissue,  together  with  some  of  the  carbon  pass  off  in  the  form 
of  carbon  dioxide  (CO2),  carbon  monoxide  (CO),  marsh  gas 
(CH4),  and  water.  As  a  result,  as  the  process  continues 
an  increasing  percentage  of  carbon  is  left  behind.  The 
change  is  also  accompanied  by  a  change  in  color  to  deep 
brown,  and  finally  to  black. 

The  changes  that  take  place  in  the  passage  of  vegetable 
matter  into  coal  are  graphically  shown  in  the  following  dia- 
gram prepared  by  the  late  Professor  Newberry  :  — 


.VEGETABLE  TISSUE 


FIG.  1.  —  Diagram  showing  changes  occurring  in  passage  of  vegetable 
tissue  to  graphite.    After  Newberry, 

In  this  diagram  the  rectangle  ABCD  represents  a  given 
volume  of  fresh  vegetable  matter,  which  contains  a  small 
percentage  of  mineral  matter,  the  rest  being  organic  sub- 
stances consisting  roughly  of  50  per  cent  carbon  (EFCD) 
and  50  per  cent  hydrogen,  oxygen,  and  nitrogen  (ABEF). 
In  the  change  from  fresh  vegetable  tissue  to  peat,  part  of 
these  four  elements  pass  off  as  gaseous  compounds,  so  that 
the  remaining  volume  of  peat  is  less  (BGDH)  than  the  origi- 
nal volume  of  vegetable  matter  (ABCD).  Since,  however, 
H,  O,  and  N  have  passed  off  in  larger  amounts  than  the 
carbon,  the  percentage  of  the  latter  in  the  peat  will  be  higher 
than  it  was  in  the  fresh  plant  tissue.  (Compare  BFGI  and 


14 


ECONOMIC   GEOLOGY   OP  THE  UNITED   STATES 


FIDH  with  ABEF  and  EFCD.)  The  actual  weight  of 
mineral  matter  will  be  the  same,  but  its  percentage  will  be 
larger.  This  change  continued  will  result  finally  in  anthra- 
cite, the  last  of  the  coal  series,  in  which  the  per  cent  of  carbon 
(LKMN)  is  high  and  that  of  the  other  organic  elements  low 
(JKL).  The  amount  of  compression  that  occurs  in  such 
changes  as  those  illustrated  in  the  diagram  may  be  under- 
stood when  it  is  stated  that  it  is  estimated  that  from  16  to 
30  feet  of  peat  are  required  to  make  one  foot  of  true  coal. 

The  following  analyses  of  various  grades  of  coal  from  peat 
to  anthracite  clearly  illustrate  this  gradual  concentration  of 
carbon  by  loss  of  volatile  elements. 

ELEMENTARY  ANALYSES  OF  COALS 


C. 

II. 

O. 

BT. 

s. 

Ash 

Mois- 
ture 

Peat      

59.47 

6.52 

31.51 

2.51 

22 

58  44 

4  97 

16  42 

1  30 

Bituminous  coal  . 

68  13 

6.49 

5.83 

2.27 

2.48 

12.30 

Breckenridge  Co.,  Ky. 
Bituminous  coal  

73.80 

5.79 

16.58 

1.52 

.41 

1.90 

Ohio 
Bituminous  coal      .... 

82.70 

4.77 

9.39 

1.62 

.45 

1.07 

Clay  Co.,  Ind. 
Anthracite 

90  45 

2  43 

245 

467 

East  Pa. 

Effect  of  Heat  and  Pressure. — While  the  first  stage  in 
coal  formation  is  brought  about  simply  by  the  exclusion  of 
air,  for  further  development  pressure  seems  necessary. 
Even  in  peat  beds  the  lower  layers  are  under  the  gentle 
pressure  of  the  upper  layers ;  but  peat  is  not  changed  even 
to  lignite  until  buried  under  many  feet  of  sediments.  Great 
pressure,  possibly  aided  by  heat,  seems  necessary  for  the 


COAL  15 

change  from  lignite  to  bituminous  coal ;  and  long  periods  of 
time  are  apparently  required  for  the  slow  changes  to  take 
place.  That  heat  may  sometimes  have  been  present  is  indi- 
cated by  the  evidence  of  rock  folding  that  is  sometimes, 
though  by  no  means  invariably,  present  in  bituminous  coal 
areas. 

Most  of  the  anthracite  coal  in  the  United  States  occurs  in 
the  highly  folded  Appalachians  of  Pennsylvania.  Such  fold- 
ing must  have  been  productive  of  much  heat  and  pressure, 
and  that  the  folding  has  produced  the  anthracite  is  by  many 
believed  to  be  proved  by  the  fact  that  these  coal  beds  pass 
into  bituminous  coal  when  traced  southward  or  westward 
into  areas  of  less  disturbances.  This  view  is  questioned  by 
some  geologists,  especially  J.  J.  Stevenson,  who  has  argued 
that  the  anthracite  has  not  been  developed  from  bituminous 
coal  by  metamorphism,  but  that  the  volatile  constituents 
were  partly  removed  by  longer  exposure  of  the  vegetable 
matter  to  oxidation  before  burial  (7). 

There  are  some  cases,  as  in  the  Cerillos  coal  field  of  New 
Mexico  (50),  where  anthracite  probably  has  been  produced 
by  heat.  Here  a  bituminous  coal  has  been  deprived  of  its 
volatile  matter  and  converted  into  anthracite  in  those  por- 
tions of  the  bed  near  an  intrusion  of  andesite.  A  similar 
change  has  taken  place  in  the  Crested  Butte  district  of 
Colorado  (29). 

Structural  Features  of  Coal  Beds.  —  Outcrops  (1,  3). — The 
outcrop  of  a  coal  bed  is  usually  easily  recognizable  on 
account  of  its  color  and  coaly  character;  but  unless  the 
exposure  is  a  rather  fresh  one,  the  material  is  disintegrated 
and  mellowed,  the  wash  from  it  mingling  with  the  soil,  and 


16 


ECONOMIC    GEOLOGY    OF   THE    UNITED   STATES 


Coal 
Fire  Clay 


Coal 
Fire  Clay 


if  the  outcropping  bed  is  on  a  hillside,  often  extending  some 
feet  down  the  slope.  This  weathered  outcrop  has  been 
termed  the  "smut"  or  "blossom"  by  coal  miners.  In 
areas  where  the  beds  have  been  tilted  and  the  slopes  are 
steep,  the  outcrops  of  coal  can  usually  be 
easily  traced ;  but  in  regions  where  the  dip 
is  low  and  the  surface  level,  the  search  for 
coal  is  often  attended  with  difficulty,  which 
is  increased  if  the  country  is  covered  with 
glacial  drift.  In  such  cases  boring  or  pit- 
ting is  commonly  resorted  to. 

Associated  Rocks.  —  Most  coal  beds  are 
interbedded  with  shales,  clays,  or  sand- 
stones, though  conglomerates  or  limestones 
are  at  times  also  found  in  close  proximity. 
Coal  beds  are  often  underlain  by  a  bed  of 
clay,  which  in  some  regions  is  of  refractory 
character  (Fig.  2);  but  the  widespread 
belief  that  all  these  under  clays  are  fire 
clays  is  unwarranted. 

Variations   in   Thickness.  —  Coal   beds   or 
Fio.  2.  — Section   in 

coal  measures  of  "seams"  are  rarely  of  uniform  thickness 
western  Pennsylva-  .  .  . 

nia,  showing  fire  over  large  areas;  indeed,  a  bed  which  is 
beTs.  Differ  H<£-  of  sufficient  thickness  to  work  in  one  mine 
kins-  may  be  so  thin  in  a  neighboring  mine  as 

to  be  scarcely  noticeable.  This  irregularity  is  in  some  cases 
due  to  variations  in  thickness  of  vegetable  accumulations, 
in  other  cases  to  local  squeezing  of  the  coal  bed  subsequent 
to  its  formation.  These  thinnings  and  thickenings  are  com- 
monly called  "pinchings"  and  "swellings"  (Fig.  3).  In 
regions  of  pronounced  folding,  the  coal  beds  are  usually 


COAL 


17 


found  in  separate  synclinal  basins,  the  intervening  anticlinal 
folds  having  been  worn  away. 

Other  Irregularities.  —  Splitting  (Fig.  3)  is  a  common 
feature  of  many  coal  seams.  The  Mammoth  bed,  so  promi- 
nent in  most  of  the  anthracite  basins  of  Pennsylvania,  splits 


FIG.  3.  —  Section  showing  irregularities  in  coal  seam,    a,  split; 
6,  parting  of  shale ;  c,  pinch ;  d,  swell;  e,  cut  out. 

into  three  separate  beds  in  the  Wilkesbarre  basin.  This 
splitting  is  caused  by  the  appearance  of  beds  of  shale  (called 
"  slate "  by  coal  miners),  which  often  become  so  thick  as 
to  split  up  the  coal  seam  into  two  or  more  beds.  When 
narrow,  such  a  bed  of  slate  is  called  a  parting.  The  Pitts- 
burg  seam  of  western  Pennsylvania  shows  a  fire-clay  parting 
or  "horseback"  (Fig.  3) 
from  six  to  ten  inches 
thick  over  many  square 
miles. 

In  addition  to  these 
"  slate "  partings,  which 
run  parallel  with  the  bed- 
ding, others  are  often 
encountered  which  cut 
across  the  beds  from  top 


Fio.  4.  —  Section    of    faulted   coal   seam. 
After  Keyes,  la.  Geol.  Surv.,  II:  86,  1894. 


to  bottom.  These  in  some  cases  represent  erosion  channels, 
formed  in  the  coal  during  or  subsequent  to  its  formation, 
and  later  filled  by  the  deposition  of  sand  or  clay.  In  other 


18  ECONOMIC   GEOLOGY   OF   THE  UNITED   STATES 

cases  they  are  due  to  the  filling  of  fissures  formed  during 
the  folding  of  the  strata. 

Faulting  (Fig.  4)  is  not  an  uncommon  feature  of  coal 
beds,  and  the  coal  is  sometimes  badly  crushed  on  either  side 
of  the  line  of  fracture.  The  amount  of  throw  and  the  num- 
ber and  kind  of  faults  may  vary,  so  that  one  might  expect 
normal,  reverse,  overthrust,  and  even  step  faults. 

Coal  Fields  of  the  United  States  (PI.  I).  — Coal  in  com- 
mercial quantities  occurs  in  twenty-seven  of  the  forty-seven 
states  and  territories  as  well  as  in  Alaska.  These  occur- 
rences can  be  grouped  into  the  following  ten  fields :  — 

(1)  Appalachian,  including  parts  of  Pennsylvania,  Ohio, 

Maryland,  Virginia,  West  Virginia,  Eastern  Ken- 
tucky, Tennessee,  Georgia,  and  Alabama     .        .    71,291  sq.  mi. 

(2)  Rhode  Island Very  small. 

(3)  Atlantic  Coast  Triassic,  including  parts  of  Virginia 

and  North  Carolina 1070  sq.  mi. 

(4)  Eastern  Interior,  including  parts  of  Indiana,  Illinois, 

and  western  Kentucky 58,000  sq.  mi. 

(5)  Northern  Interior,  including  parts  of  Michigan          .    11,300  sq.  mi. 

(6)  Western  Interior,  including  parts  of  Iowa,  Missouri, 

Nebraska,  and  Kansas      .        .        .        .        .        .    66,200  sq.  mi. 

(7)  Southwestern  field,  including  parts  of  Indian  Terri- 

tory, Arkansas,  and  Texas 27,876  sq.  mi. 

(8)  Rocky  Mountain  field,  including  parts  of  South  Da- 

kota, Montana,  Idaho,  Wyoming,  Utah,  Colorado, 

and  New  Mexico 43,610  sq.  mi. 

(9)  Pacific  Coast,  including  parts  of  Washington,  Oregon, 

and  California 1050  sq.  mi. 

(10)  Alaska : 

The  above  grouping  does  not  include  the  areas  of  lignite- 
bearing  formations,  although  these  are  shown  on  the  map 


COAL  19 

(PI.  I).  According  to  Hayes  there  are  in  Montana,  the 
Dakotas,  and  Wyoming,  approximately  56,500  square  miles 
of  lignite-bearing  formations,  chiefly  of  Cretaceous  age. 
A  series  of  fields  in  the  Tertiary  of  Alabama,  Mississippi, 
Louisiana,  Arkansas,  and  Texas  cover  approximately  as 
large  an  area. 

The  estimates  given  above  are  of  course  only  approximate,  and  some 
of  these  fields  may  be  extended  in  the  future  by  the  development  of 
areas  now  classed  as  unproductive.  This  applies  especially  to  those  in 
which  the  coal  lies  too  deep  to  be  profitably  mined  at  present.  It  is  a 
noteworthy  fact  that  the  production  of  the  fields  is  by  no  means  propor- 
tional to  their  areas.  (Compare  above  list  with  table,  p.  34.)  Proximity 
to  markets,  value  of  the  coal  for  fuel,  and  relative  quantity  of  coal  per 
square  mile  of  productive  area,  are  factors  of  importance  in  determining 
the  output  of  a  field. 

Geologic  Distribution  of  Coals  in  the  United  States.  —  The 

coal-bearing  formations  of  the  United  States  range  in  age 
from  Carboniferous  to  Tertiary.  Carboniferous  coals  occur 
east  of  the  100th  meridian,  Cretaceous  coals  between  the 
100th  and  115th  meridian,  and  the  Tertiary  coals  chiefly 
between  the  120th  meridian  and  the  Pacific  coast.  Excep- 
tions to  this  distribution  are  the  occurrence  of  a  small  area 
of  Triassic  coals  in  Virginia  and  North  Carolina,  and  a  large 
Tertiary  area  of  lignite  in  the  Gulf  States.  This  indicates 
that  during  the  coal-forming  periods  there  was  in  North 
America  a  slow  westward  shifting  of  the  zone  in  which 
conditions  favorable  to  coal  formation  occurred,  the  only 
exceptions  being  those  mentioned  above. 

The  Carboniferous  coals  are  commonly  grouped  into 
several  well-marked  and  clearly  separated  areas;  but  this 
isolation  is  probably  the  result  of  folding  and  erosion,  all 


20 


ECONOMIC    GEOLOGY   OF   THE   UNITED    STATES 


excepting  the  Michigan  field  having  apparently  been  origi- 
nally continuous.     To   a  certain   extent   the   same   is   true 


1 1 


1 


fi.u* 


of  the  Rocky  Mountain  coal  fields. 
These  have  often  been  seriously  dis- 
turbed by  post-Cretaceous  uplifts, 
which  in  many  instances  have  im- 
proved the  qualities  of  the  coal.  As 
a  whole,  the  Tertiary  coals  are  medium 
to  low  grade,  though  in  some  sections, 
notably  in  Washington,  they  are  of 
excellent  quality. 


I 


s 

in 


1-3 

«« 


Appalachian  Field  (12,  15,  18,  55,  58, 
60,  etc.).  —  This,  the  most  important 
coal  field  in  the  United  States,  ex- 
tends 850  miles,  from  northeastern 
Pennsylvania  to  Alabama,  and  about 
75  per  cent  of  its  area  contains  work- 
able coal.  At  the  southern  end  the 
coal  measures  pass  beneath  the  coastal 
plain  deposits,  and  they  may  connect 
with  the  Arkansas  coal  measures  be- 
neath the  Mississippi  embayment. 

Being  closely  associated  with  the 
Appalachian  Mountain  uplift,  the  coal 
measures  of  this  region  partake  of  the 
structural  features  of  the  Appalachian 
belt.  Thus,  while  the  strata  of  the 
western  portion  are  either  horizontal 
or  only  slightly  bent,  those  farther 
east  are  often  highly  folded  (Fig.  7),  and  in  the  southern 


ril 


COAL  21 

Appalachians  the  strata  are  both  folded  and  faulted  (Fig.  5). 
Extensive  erosion  following  the  folding  of  the  coal  meas- 
ures has  resulted  in  the  development  of  a  number  of 
basins. 

The  coal  measures  of  the  Appalachian  field  consist  of  a 
great  thickness  of  overlapping  lenses  of  conglomerate,  sand- 
stone, shale,  coal,  and  some  limestones,  and  owing  to  this 
lenticular  character  of  the  deposits,  and  to  local  thickenings, 
it  is  difficult  to  trace  individual  beds  of  coal  over  wide  areas, 
or  to  correlate  sections  at  widely  separated  points. 

The  middle  Carboniferous,  or  Pennsylvanian,  includes 
most  of  the  coal  beds  of  the  Appalachian  area,  and  is 
divided  into  the  following  five  major  subdivisions  which  are 
recognizable  throughout  the  field  :  (1)  Dunkard  or  Upper 
Barren  Measures;  (2)  Monongahela  or  Upper  Productive 
Measures ;  (3)  Conemaugh  or  Lower  Barren  Measures ; 
(4)  Alleghany  or  Lower  Productive  Measures;  (5)  Pottsville 
or  Serai  Conglomerate. 

This  classic  section  was  first  worked  out  in  Pennsylvania, 
and  has  since  been  identified  in  other  parts  of  the  Appa- 
lachian field.  At  the  time  it  was  made,  the  second  and 
fourth  members  were  thought  to  be  the  only  ones  carrying 
coal,  and  hence  the  name  "  Productive  "  ;  but  since  then  the 
Pottsville  has  been  found  to  be  locally  productive,  and  a  few 
seams  have  been  found  even  in  the  Barren  Measures. 

The  Appalachian  field  is  divisible  into  two  parts  of  very 
unequal  size :  (1)  the  anthracite  field  of  northeastern 
Pennsylvania  ;  and  (2)  the  bituminous  area,  which  occu- 
pies the  balance  of  the  field. 

Bituminous  Area  (15,  20). — In  western  Pennsylvania,  where 
we  have  the  type  section  of  the  Carboniferous  of  eastern 


22  ECONOMIC   GEOLOGY   OF  THE   UNITED   STATES 

America,  about  95  per  cent  of  the  coal  mined  comes  from 
the  Alleghany  and  Monongahela  groups,  though  beds  of 
coal  are  found  as  high  as  the  Dunkard  and  as  low  as  the 
Pottsville.  While  most  of  the  coal  beds  are  of  limited 
extent,  the  celebrated  Pittsburg  bed,  at  the  base  of  the 
Monongahela,  with  an  average  thickness  of  6  feet  over  2500 
sq.  mi.  of  its  area,  has  an  estimated  original  capacity  of 
10,000,000,000  tons  of  available  coal,  thus  making  it  one 
of  the  most  important  bituminous  coal  beds  in  the  world. 
This  same  bed  is  recognizable  and  important  in  Ohio  and 
Maryland. 

In  the  southern  portion  of  the  Appalachian  field,  the  coal 
beds  lie  in  the  Pottsville,  which  here  is  much  thicker  than 
farther  north,  reaching  a  maximum  thickness  of  5000  to  6000 
feet,  as  against  300  feet  in  western  Pennsylvania,  and  most 
of  the  workable  coal  occurs  in  its  upper  portion. 

Character  of  Appalachian  Bituminous  Coals. — The  coals  of  this  field 
differ  greatly  from  place  to  place.  In  general  there  is  a  decrease  in 
volatile  hydrocarbons  from  the  west  toward  the  east  and  southeast. 
Good  coking  coals  are  found  throughout  the  field.  Those  of  Maryland 
are  semi-bituminous,  and  have  a  high  reputation  for  steaming  purposes ; 
but  those  of  Pennsylvania  include  many  coking  coals,  and  are  hence  of 
further  value  in  smithing,  and  coke  and  gas  manufacture.  While  much 
of  the  coke  is  used  locally  by  the  great  metallurgical  establish- 
ments, a  large  amount  is  also  shipped  to  other  states,  even  in  the 
far  Northwest. 

The  markets  for  these  coals  are  chiefly  in  the  South  where,  excepting 
along  the  seacoast,  they  come  into  successful  competition  with  the  Penn- 
sylvania anthracite  for  domestic  purposes.  In  the  north  and  northwest 
they  compete  less  successfully  with  coals  from  the  interior  fields. 

Pennsylvania  Anthracite  Meld  (18).  — This  field  (Fig.  6) 
lies  in  the  eastern  central  part  of  the  state,  covering  an  area 


COAL 


23 


of  about  3300  square  miles,  about  one-seventh  of  which 
is  underlain  by  workable  coal  measures.  Intense  folding 
(Fig.  7)  has  placed  some  of  the  coal  in  the  synclinal  troughs 
where  it  has  been  preserved  from  erosion  which  has  removed 
the  coal  from  the  intervening  anticlines.  Therefore  the 
anthracite  is  found  in  a 
number  of  more  or  less 
separated  narrow  basins. 
It  has  been  estimated  that 
from  94  to  98  per  cent  of 
the  coal  originally  depos- 
ited has  been  removed  from 
this  field  by  denudation. 

The  coal  measures  of  the 
anthracite  district  consist 
of  beds  of  sandstone,  shale, 
and  clay,  with  coal  beds  at 
intervals  varying  from  a 
few  feet  to  several  hundred 
feet,  though  rarely  exceed- 
ing 200  feet.  The  coal 
beds,  which  vary  in  thick- 
ness from  a  few  inches  to  50  or  60  feet,  occur  through- 
out the  entire  section  of  the  coal  measures,  but  are  most 
important  in  the  lower  300  to  500  feet.  Beneath  the  Pro- 
ductive Measures  is  the  hard  Pottsville  conglomerate, 
which  forms  an  important  stratigraphic  horizon,  recogniz- 
able by  its  lithological  character  and  bold  outcrops.  Local 
variations  in  the  coal  beds,  and  lack  of  uniformity  in  naming 
them,  have  rendered  their  correlation  in  the  different  fields 
more  or  less  difficult. 


FIG.  6.  —  Map  of  Pennsylvania  anthracite 
field.  After  Stoek,  U.  S.  Geol.  Surv., 
22d  Ann.  Sept.,  III. 


24 


ECONOMIC  GEOLOGY  OF  THE  UNITED  STATES 


The  position  of  the  coal  beds  and  physical  characteristics  of  the  coal 
have  necessitated  the  use  of  special  methods  of  mining  and  of  treat- 
ment after  mining.  Sharpness  of  folding  and  steep  dips  prevail,  these 
introducing  many  mining  problems  not  found  in  bituminous  regions. 
When  brought  to  the  surface,  it  consists  of  lumps  varying  in  size  and 
mixed  with  more  or  less  shaly  coal,  called  "  bone,"  so  that,  before  ship- 
ment to  market,  it  is  necessary  to  break,  size,  and  sort  it.  This  is  done 


3         jj&nu      B«.   SkJUUlWl^S  Coll  K»a  BuialS 

Ijs^ljll— -illy* 


\       / 


Section  (C)jcroM  the  J&mther  Creek  Bwla 


FIG.  7  .  —  Sections  in  Pennsylvania  anthracite  field.      After  Stock,  U.  S.  Geol. 
Surv.,  2?2d  Ann.  Rept.,  Ill:  72. 

in  a  coal  breaker  (Fig.  8),  in  which  the  coal  is  ci-ushed  in  rolls,  and  sized 
by  screens,  while  the  slate  is  separated  either  by  hand,  automatic  pickers, 
or  jigs.  These  breakers  are  a  prominent  feature  of  the  anthracite  region, 
and  much  money  has  been  spent  in  increasing  their  efficiency.  As  the 
result  of  years  of  mining,  the  refuse  from  the  breakers,  consisting  of  a 
fine  coal-dust  and  bone,  termed  "culm,"  has  accumulated  in  enormous 
piles.  Much  of  it  is  now  being  washed  to  save  the  finer  particles  of 
clean  coal ;  and  much  is  also  washed  into  the  mines  to  support  the  roof, 
so  that  the  pillars  of  coal,  originally  left  for  that  purpose,  can  be 
extracted. 


COAL  25 

On  account  of  its  cleanliness  and  high  fuel  ratio,  anthra- 
cite coal  is  much  prized  for  domestic  purposes.  Most  of  that 
mined  is  marketed  in  the  eastern  and  middle  states,  although 
small  quantities  are  shipped  to  the  western  states*  especially 
those  that  can  be  reached  by  way  of  the  Great  Lakes. 


FIG.  8.  —  Coal  breaker  in  Pennsylvania  anthracite  region. 

Rhode  Island  Field  (63,  H4).  —  A  small  area  of  metamorphosed,  folded, 
and  faulted  Carboniferous  occurs  in  the  Narragansett  Bay  region  of 
Rhode  Island,  extending  up  into  Massachusetts.  The  inclosing  strata 
of  conglomerate  and  clay  are  often  changed  to  schist,  and  the  coal  to  a 
form  of  anthracite  so  nearly  pure  carbon  as  to  be  exceedingly  difficult 
to  burn.  In  fact,  in  places  the  coal  has  been  metamorphosed  to  graphite. 
Attempts  to  utilize  this  have  not  met  with  much  success  on  account  of 
the  high  percentage  of  impurities  which  the  material  contains. 

The  Triassic  Field  (52).  —  This  coal  field  which  is  more  important 
historically  than  economically,  having  been  worked  as  early  as  1700, 
includes  several  small  steep-sided  basins  lying  in  the  Piedmont  region  of 
Virginia  and  North  Carolina.  It  is  probable  that  the  coal-bearing  beds 
of  the  several  areas,  originally  horizontal,  were  formerly  continuous, 
having  been  separated  by  folding,  faulting,  and  denudation.  In  addition 
to  this,  the  coal  is  cut  by  dikes  and  sheets  of  igneous  rock,  which  have 
locally  altered  it  to  natural  coke  or  carbonite. 


26 


ECONOMIC  GEOLOGY  OF  THE  UNITED  STATES 


Eastern  Interior  Field  (13,  32).  —This 
field  is  an  oval,  elongated  basin  (Fig. 
9)  extending  northeast  and  southwest, 
with  the  marginal  beds  dipping  gently 
toward  the  lowest  portion,  which  lies 
in  Illinois,  where  the  beds  are  nearly 
horizontal. 

The  coal-bearing  rocks  rest  uncom- 
formably  on  lower  Carboniferous,  Devo- 
nian, and  Silurian  strata,  the  basal 
member  being  a  sandstone  probably  the 
equivalent  of  the  Pottsville.  The 
entire  section  of  coal-bearing  rocks, 
attaining  a  thickness  of  1200  feet, 
belongs  to  the  Coal  Measures,  although 
the  upper  part  may  be  of  Permian  age, 
and  the  highest  workable  coal  beds  are 
classed  as  Freeport  or  Conemaugh. 
The  coal  seams  occur  in  the  lower 
portion  of  the  section,  and  hence  out- 
crop around  the  margin,  and  the  mining 
operations  are  confined  to  a  narrow  belt, 
because  near  the  center  of  the  basin  the 
coal  beds  underlie  too  great  a  thick- 
ness of  unproductive  strata  to  permit 
of  profitable  working  under  present 
conditions. 

Great  difficulty  has  been  encountered 
in  attempts  at  correlation  of  the  coal 
beds  of  different  parts  of  the  field,  be- 
cause of  the  varying  section  shown 


COAL 


27 


from  place  to  place,  and  lack  of  continuity  of  the  beds. 
In  consequence,  the  custom  has  arisen  of  giving  the  coal 
beds  numbers  instead  of  names. 

In  Indiana  coal  is  found  in  at  least  twenty  horizons  with  workable  beds 
in  not  less  than  eight ;  but  at  any  given  point  the  number  of  workable 
beds  never  exceeds  three,  and  in  places  there  is  only  one.  One  of  the 
Indiana  coals  is  known  as  "  block  coal,"  the  name  arising  from  the  fact 

that  the   presence       ^__^__ 

of  joint  planes  at 
right  angles  causes 
the  coal  to  break 
into  blocks. 

There  are  many 
coal  beds  in  Illinois 
worked  at  depths 
of  from  50  to  200 
feet  or  more;  but 
there  is  a  marked 
absence  of  stratigraphic  knowledge  regarding  this  part  of  the  field. 
In  Kentucky,  on  the  other  hand,  there  are  only  two  workable  coal  beds 
of  decided  importance,  and  fully  75  per  cent  of  the  coal  produced  in  the 
strata  comes  from  the  upper  of  these.  This  bed  is  so  persistent  that  it 
underlies  a  part  of  the  whole  of  8  counties,  with  an  average  thickness  of 
5  feet  and  at  a  depth  commonly  less  than  200  feet. 

The  coals  of  the  eastern  interior  field,  although  varying  widely  in 
quality,  are  all  bituminous.  On  account  of  their  higher  percentage  of 
ash  and  sulphur,  they  are  little  used  for  coking.  Most  of  the  coal  used 
in  and  near  this  field  is  supplied  from  it ;  but  even  within  the  field  the 
Appalachian  coals  enter  into  competition.  The  Cannel  coal  found  near 
Cannelsburg,  Kentucky,  which  is  the  only  good  gas  producer  found  in 
this  field,  finds  a  ready  market. 

Northern  Interior  Field  (43).  —  This  field  forms  a  large 
basin  in  which  the  coal  dips  irregularly  from  the  margin 
toward  the  center  (Fig.  11),  but  on  account  of  the  heavy 


FIG.  10.  —  Shaft  house  and  tipple,  bituminous  coal  mine, 
Spring  Valley,  111. 


28  ECONOMIC   GEOLOGY   OF   THE  UNITED   STATES 

mantle  of  glacial  drift  it  has  been  difficult  to  determine 
its  exact  boundaries,  and  prospecting  is  necessarily  done 
by  means  of  drilling.  The  coal  measures  attain  a  total 
thickness  of  600  to  700  feet  in  the  center  of  the  basin,  and 
include  7  horizons  of  workable  coal  with  an  average 
thickness  of  2  feet  and  rarely  exceeding  4  feet.  Coal 
is  found  near  the  center  of  the  basin  at  depths  of  400 
feet  or  more,  though  the  beds  that  are  mined  are  mostly 


SO          IOC         I5O         ZOOibct 


Fia.  11.  —  Generalized  section  of  Northern  Interior  coal  field.    After" Lane, 
U.  S.  Geol.  Surv.,  Z2d  Ann.  Kept.,  Ill:  316. 

at  depths  of  100  to  250  feet.  All  the  coals  are  bituminous 
and  used  chiefly  for  fuel,  but  some  are  coking,  and  others 
will  probably  prove  of  value  for  gas  manufacture. 

Western  Interior  Field  and  Southwestern  Fields  (U). — 
These  two  fields  form  a  practically  continuous  belt  of  coal- 
bearing  formations,  extending  from  northern  Iowa  south- 
westward  for  a  distance  of  880  miles  into  central  Texas. 
Throughout  most  of  this  area  the  beds  lie  horizontal,  or 
have  a  gentle  westward  dip  averaging  10  to  20  feet  per  mile. 
A  notable  exception  is  found  in  the  beds  of  eastern  Indian 
Territory  and  Arkansas  which  are  rather  strongly  folded, 
reminding  one  of  the  Pennsylvania  anthracite  area. 


COAL 


29 


Western  Interior  Field.  —  The  coal  measures,  composed  of 
limestones,  sandstones,  shales,  fireclays,  and  coal  beds,  rest 
unconformably  on  the  Mississippian  and  dip  westwardly 
under  beds  of  Permian,  Cretaceous,  and  Pleistocene  (Fig.  12). 
Toward  the  south  and  west  the  beds  increase  in  thickness, 
the  maximum  being  1000  feet  in  Iowa  (36)  and  3000  in 
Kansas  (37). 

Most  of  the  coal  mined  in  this  field  comes  from  the  lower 
part  of  the  coal  measures  where  the  beds  are  irregular  in 


FIG.  12. — Composite  section  showing  structure  of  lower  coal  measures  of  Iowa. 
After  Keyes,  la.  Geol.  Surv.,  I:  105. 

thickness  and  distribution,  in  consequence  of  deposition  on 
a  very  uneven  surface. 

All  the  coals  of  this  field  are  essentially  bituminous  and  used  chiefly 
for  steaming  and  heating  purposes,  being  of  no  value  for  either  coking 
or  gas  making.  Some  of  the  seams  will  coke,  but  there  is  no  demand  for 
the  product,  and  the  sulphur  and  ash  are  too  high  for  gas  making. 

Southwestern  Field.  —  While  it  is  known  that  there  is 
much  good  coal  in  this  field,  full  development  has  not  been 
undertaken  in  most  parts  of  it.  The  Indian  Territory 
coals  (34, 35),  of  which  there  are  7  important  beds  in  a 
section  of  4500  feet  of  shales  and  sandstone,  are  both  folded 
and  faulted.  These  coals,  as  well  as  those  of  Texas  (69), 
where  there  are  three  workable  beds,  are  all  bituminous; 


30     ECONOMIC  GEOLOGY  OF  THE  UNITED  STATES 

but  in  the  eastern  end  of  the  Arkansas  (25)  field  there  is 
anthracitic  coal  of  probable  Permian  age. 

The  coal  from  this  field  finds  its  most  important  market 
in  the  South,  though  some  is  sent  North.  The  Texas  coals 
are  of  especial  importance  on  the  railways,  being  used  as 
far  west  as  the  Pacific  coast.  It  has,  however,  found  a 
serious  competitor  in  the  Texas  crude  petroleum;  but  it 
remains  to  be  seen  whether  this  competition  will  be  lasting. 
On  account  of  the  value  for  domestic  purposes  the  anthra- 
cite finds  an  important  market  to  the  northward. 

Gulf  States  Lignite  Area  (9).  — There  is  a  narrow  lignite- 
bearing  belt  extending  across  the  lower  part  of  Alabama 
and  Mississippi;  and  another  much  larger  belt  extending 
from  near  Little  Rock,  Arkansas,  southwestward  across  the 
northwestern  corner  of  Louisiana  (42),  and  in  a  narrowing 
belt  across  Texas.  Both  of  these  are  of  Eocene  age.  The 
lignites  are  usually  high  in  moisture  and  ash,  the  best  grade 
being  that  mined  in  the  lower  end  of  the  area,  near  Laredo 
on  the  Rio  Grande. 

A  small  field  of  Cretaceous  lignitic  coal  has  been  devel- 
oped around  Eagle  Pass  on  the  Rio  Grande  (70).  This 
is  an  extension  of  the  Mexican  field,  but  is  of  poorer 
quality. 

Rocky  Mountain  Fields  (17). — These  cover  a  broad  area, 
extending  from  the  Canadian  boundary  southward  into 
New  Mexico,  a  distance  of  about  1000  miles,  and  includ- 
ing over  50  fields  of  various  size  and  irregular  shape. 
Most  of  the  beds  lie  within  the  mountainous  region,  but  at 
the  northern  end  of  the  area,  in  Wyoming  and  the  Dakotas, 
the  coal  fields  extend  eastward  under  the  plains  for  some 


PLATE  II 


FIG.  1.  —  Pit  working  (Strippings)  near  Milnesville,  Pa.    The  Mammoth  seam  is 
uncovered  in  bottom  of  pit. 


FIG.  2.  —  Lignite  seam,  Williston,  N.D.     After  Wilder  photo. 


COAL  31 

distance.      The  age  of  the  coal  ranges  from  Cretaceous  to 
Tertiary,  though  most  of  it  belongs  to  the  former. 

While  portions  of  this  enormous  area  of  coal-bearing 
strata  are  only  slightly  disturbed,  mountain-building  forces 
and  igneous  intrusions  have  affected  a  large  proportion  of 
the  region,  often  materially  changing  the  character  of  the 
coal.  Thus,  while  in  undisturbed  portions  of  the  field  the 
beds  are  lignitic  (PI.  II,  Fig.  2),  in  the  disturbed  parts  they 
have  been  altered  to  bituminous  and  even  to  anthracite 
coal.  Some  of  the  bituminous  coals  produce  an  excellent 
quality  of  coke. 

Colorado  (29,  30)  is  the  most  important  coal-producing  state  of  the 
Rocky  Mountain  region.  This  is  due,  not  only  to  the  quality  of  its 
coals,  but  also  to  the  presence  within  the  state  of  extensive  metal- 
lurgical industries.  The  Raton  field,  in  the  southeastern  part  of  the 
state  and  extending  into  New  Mexico  (50,  51),  is  at  present  the  most 
important  producer.  Like  many  of  the  fields  of  this  region  the  age 
of  these  is  Laramie,  and  the  beds  are  both  folded  and  faulted.  They 
are,  moreover,  crossed  by  igneous  intrusions  which  have  in  some  places 
produced  natural  coke,  but  in  others  destroyed  the  value  of  the  coal. 
In  a  section  of  from  3000  to  4500  feet  of  Laramie  strata  there  are  40 
coal  beds,  only  a  few  of  which  are,  however,  workable.  There  are 
both  coking  and  semi-coking  coals,  and  some  anthracite. 

In  Montana  (45,  46,  47)  the  coals  range  in  age  from  Triassic  to  Ter- 
tiary, and  in  quality  from  lignite  to  bituminous.  The  coals  of  Wyoming, 
which  occupy  a  very  large  area,  show  the  same  range  in  quality,  but 
are  more  commonly  lignite  because  found  to  so  large  an  extent  in  re- 
gions of  slight  disturbance.  The  Utah  coals  are  prevailingly  semi- 
bituminous,  and  those  of  the  two  Dakotas  lignitic. 

The  Pacific  Coast  Fields  (16).  —  Tertiary  coals,  partly 
bituminous,  though  mainly  lignitic,  occur  scattered  over  a 
wide  area  in  the  states  of  California  (28),  Washington  (75), 


32  ECONOMIC   GEOLOGY   OF   THE   UNITED   STATES 

and  Oregon  (56,  57).  The  separate  fields  are  limited  in  ex- 
tent, widely  separated,  and  with  a  small  total  output.  Of 
the  four  fields  recognized  in  Washington,  the  most  impor- 
tant lie  directly  east  of  Seattle  arid  Tacoma.  The  total 
thickness  of  coal-bearing  sandstones  and  strata  is  about 
10,000  feet,  but  important  coal  beds  are  found  only  in  the 
lower  2000  feet.  It  is  stated  that  there  are  100  coal  seams 
of  sufficient  thickness  to  attract  the  prospector ;  and  in  a 
single  district  there  may  be  from  5  to  10  workable  beds. 
Since  the  quality  of  the  coal  varies  with  the  extent  of 
dynamic  disturbance,  there  is  considerable  variation  even 
in  a  single  field,  and,  in  fact,  in  a  single  mine. 

Both  California  and  Oregon  produce  small  quantities  of  lignitic  coal 
of  Tertiary  age,  but  show  no  promise  of  becoming  important  producers. 
Indeed,  the  coal-trade  conditions  of  the  Pacific  coast  are  unique.  The 
local  supply  is  not  equal  to  the  demand,  and  the  Rocky  Mountain  fields 
are  too  far  off  to  supply  the  Pacific  coast  with  cheap  fuel.  Therefore 
much  coal  is  imported,  bringing  about  a  competition  in  San  Francisco 
from  many  countries,  including  England,  Wales,  Scotland,  Australia, 
Japan,  and  British  Columbia.  These  foreign  coals  are  all  of  better 
quality  than  the  Pacific  coast  coals,  and  they  can  be  imported  with 
low  freight  rate  as  ballast  in  wheat-carrying  vessels  that  come  to  San 
Francisco  for  cargoes.  These  coal  imports  form  three-quarters  of  the 
total  import  coal  tonnage  of  -the  United  States ;  but  since  1895  there 
has  been  a  steady  decrease  in  the  importation  of  coal  and  an  increase 
in  the  Pacific  coast  production. 

Alaska  (23,24).  —  Although  Alaskan  coal  was  first  mined 
in  1852  at  Port  Graham,  the  resources  of  the  region  are 
still  but  little  known  and  slightly  developed.  The  ex- 
plorations for  gold  during  the  last  few  years,  together 
with  the  field  work  done  by  the  United  States  Geological 


COAL 


33 


Survey,  have  proved  that  coal  is  widely  distributed  in  the 
Alaskan  Territory  (Fig.  81).  So  far  as  known  the  coal 
beds  are  all  in  Mesozoic  and  Tertiary  formations.  While 
most  of  the  coal  is  lignitic,  there  is  considerable  bitumi- 
nous coal  and  some  semi-anthracite. 

Coal  mining  has  been  carried  on  at  a  number  of  localities,  especially 
along  the  rivers  and  coast.  The  higher  grade  coals  along  the  coast,  par- 
ticularly in  the  southern  part  where  shipments  can  be  made  throughout 
the  year,  will  doubtless  be  developed  with  profit  in  the  near  future. 
Coals  in  the  Yukon  Valley,  though  of  low  grade  and  variable  character, 
bring  $15  a  ton  at  the  mines  because  of  the  local  demand  in  the  mining 
camps.  The  effect  of  such  a  local  demand  on  the  coal  is  even  more 
strikingly  shown  by  the  fact  that  the  semi-bituminous  coal  near  the 
Cape  Nome  gold  field  sold,  at  times,  for  as  much  as  f  100  per  ton. 

Production  of  Coal.  —  While  coal  mining  in  the  United 
States  began  at  an  early  date,  the  figures  of  production  for 
the  first  few  years  are  more  or  less  incomplete.  The  phe- 
nomenal growth  of  the  coal-mining  industry  is  well  shown, 
however,  by  the  following  figures :  — 


YEAR 

QUANTITY 
SHORT  TONS 

YEAR 

QUANTITY 
SHORT  TONS 

1868 

31  648  960 

1890 

157  770  963 

1870  

36  806  560 

1895   .    .  . 

193  117530 

1875 

5'}  *>88  3^0 

1900 

959  684  0'?7 

1880  

76  157  944 

1903   .... 

357  356  416 

1885 

111  159  795 

The  production  and  value  of  the  coal  produced  by  the 
12  largest  producers  in  point  of  output  since  1901  has 
been  as  follows:  — 


ECONOMIC    GEOLOGY   OF    THE   UNITED    STATES 


1901 

1902 

1903 

STATE 

QUANTITY 

QUANTITY 

QUANTITY 

SHORT 

VALUE 

SHORT 

VALUE 

SHORT 

VALUE 

TONS 

TONS 

TONS 

Pennsylvania  : 

Anthracite 

67,471,667 

112,504,020 

41,373,595 

76,173,586 

74,607,068 

152,036,448 

Bituminous 

82,305,946 

81,397,586 

98,574,367 

106,032,460 

103,117,178 

121,752,759 

Illinois 

27,331,552 

28,163,937 

32,939,373 

33,945,910 

36,957,104 

43,196,80!) 

West  Virginia 

24,068,402 

20,848,184 

24,570,826 

24,748,658 

29,337,241 

34,297,01!) 

Ohio 

20,943,807 

20,928,158 

23,519,894 

26,953,789 

24,838,103 

31,932,327 

Alabama 

9,099,052 

10,000,892 

10,354,570 

12,419,666 

11,654,324 

14,246,798 

Indiana 

6,918,225 

7,017,143 

9,446,424 

10,399,660 

10,794,692 

13,244,817 

Colorado 

5,700,015 

6,441,891 

7,401,343 

8,397,812 

7,423,602 

9,150,!U:} 

Kentucky 

5,469,986 

5,213,076 

6,766,984 

6,666,967 

7,538,032 

7,97!),:U2 

Iowa 

5,617,499 

7,822,805 

5,904,766 

8,660,287 

6,419,811 

10,563,910 

Maryland 

5,113,127 

5,046,491 

5,271,609 

5,579,869 

4,846,165 

7,189,784 

Kansas 

4,900,528 

5,991,599 

5,266,065 

6,862,787 

5,839,976 

8,871,953 

Tennessee 

3,633,290 

4,067,389 

4,382,968 

5,399,721 

4,798,004 

5,979,830 

Grouping  the  output  by  fields,  the  overwhelming  impor- 
tance of  the  Appalachian  field  is  well  seen. 

PRODUCTION  OF  COAL  IN  UNITKD  STATES  BY  FIELDS  FROM 
1901-1903 


FIELD 

1901 
SHORT  TONS 

1902 
SHORT  TONS 

1903 
SHORT  TONS 

Anthracite  (Pa.,  Colo.,  N.  Mex.) 
Triassic  .     .     . 

67,538,536 
12,000 
150  501  214 

41,467,532 
39,206 
173,974,861 

74,679,799 
35,393 
185,600  161 

Northern     

1,241,241 

964,718 

1,367,619 

37  450  871 

46  133,024 

52,130,856 

Western  

19,665,985 

20,727,495 

23,171,692 

Rocky  Mt              .                   .     . 

14  090  362 

16  149,545 

16,981,059 

Pacific  Coast    

2,799,607 

2,834,058 

3,389,837 

The  average  price  of  anthracite  coal,  per  short  ton,  in 
1903  was  $2.04,  while  that  of  bituminous  was  $1.24. 


COAL  35 

The  exports  in  1903  amounted  to  2,008,857  long  tons  of 
anthracite,  valued  at  $9,680,044,  and  6,303,241  long  tons  of 
bituminous,  valued  at  $17,410,385. 

PRODUCTION  OF  LEADING  COAL-PRODUCING  COUNTRIES 

COUNTRY  SHORT  TONS 

United  States  (1903) 357,356,416 

Great  Britain  (1903) 257,974,605 

Germany  (1903)       . 178,916,600 

Austria-Hungary  (1902) 43,518,319 

France  (1903) 38,583,798 

Belgium  (1903) 26,312,805 

Russia  (1902) 17,090,835 

Japan  (1901) 9,861,107 

Production  of  Coke.  —  The  quantity  of  coke  now  produced 
annually  in  the  United  States  is  very  large,  and  there  is 
an  extensive  demand  for  it  in  smelting  operations.  In 
1903  there  were  produced  25,262,360  short  tons  of  coke 
from  39,410,729  short  tons  of  coal,  which  gave  an  average 
yield  of  64.1  per  cent  coke  per  ton  of  coal,  with  the  aver- 
age value  of  $2.63  per  ton  coke.  This  quantity  was  supplied 
by  77,188  coke  ovens,  and  over  50  per  cent  of  the  supply 
came  from  Pennsylvania.  In  addition  1,882,394  short  tons, 
or  7.4  per  cent  of  the  total  production,  was  made  in  by- 
product coke  ovens,  the  approximate  percentage  of  by- 
products obtained  from  a  ton  of  coal  being:  coal  tar,  12.55 
gallons;  ammonia  liquor,  14.4  gallons;  ammonium  sulphate, 
17.6  pounds. 

REFERENCES  ON  COAL 

GENERAL.  1.  Catlett,  Amer.  Inst.  Min.  Engrs.,  Trans.  XXX :  559, 1901. 
(Coal  outcrops.)  2.  Bain,  Jour.  Geol.  Ill:  646,  1895.  (Structure 
of  coal  basins.)  3.  Lesley,  Manual  of  Coal  and  its  Topography; 
Philadelphia,  1856.  4.  Lesquereux,  2d  Geol.  Surv.  Pa.,  Ann.  Kept., 
p.  95,  1885.  (Origin.)  5.  Lyell,  Amer.  Jour.  Sci.  CLV :  353,  1843. 


36  ECONOMIC   GEOLOGY   OF   THE   UNITED   STATES 

(Upright  trees  in  coal.)  6.  Moffat,  Amer.  Inst.  Min.  Engrs., 
Trans.  XV:  819,  1887.  (Change  of  mine  prop  to  coal.)  7.  Steven- 
son, Geol.  Soc.  Amer.  Bull.,  V  :  39,  1893.  (Origin  Pa.  anthracite.) 
8.  Wormley,  Geol.  Surv.,  Ohio,  VI:  403,  1870.  (Proximate  and 
ultimate  analysis.)  See  also  Nos.  32,  32a,  37,  55. 

GENERAL  AREAL  REPORTS.  9.  Hayes,  U.  S.  Geol.  Surv.,  22d  Ann. 
Kept.,  Ill:  7,  1902.  (U.  S.  coal  fields.)  10.  MacFarlane,  Coal 
Regions  of  America,  700  pp.,  3d  ed.,  1877,  New  York.  11.  Nich- 
olls,  The  Story  of  American  Coals,  1897  (Phila.).  12.  White,  U.  S. 
Geol.  Surv.,  Bull.  65.  '  (Bituminous  field,  Pa.,  Ohio,  and  W.  Va.) 
13.  Series  of  papers  on  the  several  coal  fields  of  the  United 
States,  in  U.  S.  Geol.  Surv.,  22d  Ann.  Rept.,  Ill:  11-571,  1902,  as 
follows:  Ashley,  "p.  271.  (Eastern  Interior.)  14.  Bain,  p.  339. 
(Western  Interior.)  lo.  Hayes,  p.  233.  (Southern  Appalachians.) 
16.  Smith,  p.  479.  (Pacific  coast.)  17.  Storrs,  p.  421.  (Rocky 
Mountain  field.)  18.'  Stoek,  p.  61.  (Pa.  anthracite.)  19.  Taff, 
p.  373.  (Southwestern.)  20.  White,  Campbell,  and  Hazeltine, 
p.  125.  (Northern  Appalachians.) — Alabama:  21.  Gibson,  Ala. 
Geol.  Surv.,  1895.  (Coosa  field.)  22.  McCalley,  Ala.  Geol.  Surv., 
1900.  (Warrior  field.)  —  Alaska :  23.  Ball,  U.  S.  Geol.  Surv.,  17th 
Ann.  Rept.,  I:  771,  1896.  (Coal  and  lignite.)  24.  Brooks,  Ibid., 
22d  Ann.  Rept.,  Ill:  521.  — Arkansas:  25.  Taff,  U.  S.  Geol.  Surv., 
21st  Ann.  Rept.,  II:  313.  (Camden  field.)  —  Arizona :  26.  Blake, 
Amer.  Geol.,  XXI :  345,  1898.  27.  Campbell,  U.  S.  Geol.  Surv., 
Bull.  225 :  240,  1904.  (Deer  Creek  field.)  —  California :  See  Pacific 
Coast  Report  referred  to  above  and  also  various  county  reports  in 
(28)  llth  Ann.  Rept.  Calif.  State  Mining  Bureau.  —  Colorado: 
29.  Eldridge,  U.  S.  Geol.  Surv.,  Geol.  Atlas  of  the  U.  S.,  folio  9. 
(Anthracite.)  30.  Hills,  U.  S.  Geol.  Surv.,  Min.  Res.,  1892,  319.— 
Georgia:  31.  McCallie,  Ga.  Geol.  Surv.,  Bull.  12,  1904.  (General.) 
—  Iowa:  32 a.  Keyes,  la.  Geol.  Surv.,  II  :  1894.  (General.) —Indi- 
ana: 32.  Ashley,  Ind.  Dept.  of  Geol.  and  Nat.  Hist.,  23d  Ann. 
Rept.,  1899:  1.  — Illinois:  33.  Also  Worthen  and  others,  111. 
Geol.  Surv.,  1 : 1866 ;  III :  1868 ;  IV :  1870 ;  V :  1873  and  VI :  1875.  — 
Indian  Territory  :  34.  Adams,  U.  S.  G.  S.,  21st  Ann.  Rept.,  II :  257, 1900. 
(Eastern  Choctaw  field.)  35.  Taff,  White,  and  Girty,  U.  S.  Geol. 
Surv.,  19th  Ann.  Rept.,  Ill :  423,  1898.  (McAlester-Lehigh  field.)  — 
Iowa:  36.  Keyes,  Iowa  Geol.  Surv.,  II:  536.  — Kansas:  37.  Ha- 
worth  and  Crane,  Kas.  Univ.  Geol.  Surv.,  Ill:  13,  1898.  — Ken- 
tucky: 38.  Moore,  Ky.  Geol.  Surv.,  Ser.  2,  IV,  pt.  XI:  423.  (Eastern 
border  and  Western  field.)  39.  Lesley,  Ky.  Geol.  Surv.,  IV:  443, 
1858.  (Eastern.)  40.  Norwood,  Ann.  Rept.,  Inspector  of  Mines, 
1901-1902.  (Much  general  information.)  41.  For  analyses,  see 


COAL  37 

Ky.  Geol.  Surv.,  New  Series,  Chem.  Kept.,  etc.,  pt.  I,  II,  and  III.  — 
Louisiana:  42.  Harris,  Prelim.  Kept,  on  Geol.  of  Louisiana  for 
1899:  134.  (Lignite.)  — Maryland:  42a.  Clark,  Md.  Geol.  Surv.,  Vol. 
V,  1905.  —  Michigan :  43.  Lane,  Mich.  Geol.  Surv.,  VIII:  pt.  2.— 
Missouri:  44.  Winslow,  Mo.  Geol.  Surv.,  1891:  19-226.  — Montana: 
45.  Weed,  Eng.  and  Min.  Jour.,  LIII:  520,  542,  and  LV:  197,  also 
Geol.  Soc.  Amer.,  Bull.  111:301,  1892.  (Great  Falls  and  Rocky 
Fork  fields.)  46.  Rowe,  Amer.  Geol.,  XXXII:  369,  1903. 
47.  Burchard,  U.  S.  Geol.  Surv.,  Bull.  225:276,  1904.  (Lignites, 
Upper  Missouri  Valley.)  — Nebraska:  48.  Barbour,  Neb.  Geol.  Surv., 
I:  198,  1903.  — Nevada:  49.  Spurr,  U.  S.  Geol.  Surv.,  Bull.  225: 
289,  1904.— New  Mexico:  50.  Johnson,  Sch.  of  M.  Quart.,  XXIV: 
456.  (Cerillos.)  51.  Stevenson,  N.  Y.  Acad.  Sci.,  Trans.  XV:  105, 
1896.  (Cerillos  field.)  — North  Carolina:  52.  Woodworth,  U.  S. 
Geol.  Surv.,  22d  Ann.  Rept.,  Ill:  31,  1902.  —  North  Dakota: 

53.  Babcock,  N.  Dak.  Geol.   Surv.,  1st  Biennial  Rept.,   1901  :  56. 

54.  Wilder,  Eng.  and  Min.  Jour.,  74:  674,  1902.     (Lignite.)     Ohio: 

55.  Orton,  Ohio  Geol.  Surv.,  VII:  255.  — Oregon:  56.  Diller,  U.  S. 
Geol.  Surv.,  17th  Ann.  Rept.,  I.     (N.  W.  Ore.)     57.  Diller,  Ibid., 
19th  Ann.  Rept.,  Ill:  309.     (Coos  Bay.)  —  Pennsylvania :  58.  d'ln- 
villiers,  2d  Pa.  Geol.  Surv.  Rept,  1885  and  1886.     (Pittsburg  re- 
gion.)     59.  McFarlane,   Coal   Regions  of   America,  3d  ed. ;   New 
York,  1877.     60.   Rept.  MM.  contains  many  analyses.     61.  See  also 
various  county  reports  of  same  survey.     62.  Final  Summary  Rept., 
Ill:  pt.  1,  and  2.  — Rhode  Island:  63.  Emmons,  Amer.  Inst.  Min. 
Eng.,  Trans.  XIII :   510,  1885.      64.    Stevenson,  Manchester  Geol. 
Soc.,  Trans.   XXIII:    127.     (New   Eng.  fields.)  —  South   Dakota: 
65.  Todd,  S.  Dakota  Geol.  Surv.,  Bull.  1 :  159.  —  Tennessee :  66.  Duf- 
field,  Eng.  and  Min.  Jour.,  LXXIV :  442,  1902.     (Cumberland  Pla- 
teau.)  67.  Safford,  U.  S.  Geol.  Surv.,  Min.  Res.,  497,  1892.  — Texas: 
68.    Dumble,  Bull,  on  Lignites  of  Texas,  Tex.  Geol.  Surv.     (Lig- 
nites.)    69.   PhiUips,   Univ.    Tex.   Mineral   Surv.,  Bull.   3:    1902. 
(Coal  and   lignite.)     70.    Vaughan,   U.  S.  Geol.  Surv.,  Bull.  164, 
1900.    (Rio  Grande  fields.)  —  Utah :  71.    Forrester,  U.  S.  Geol.  Surv., 
Min.  Res.,  511,  1892.  —  Vermont :  72.    Hitchcock,  Amer.  Jour.  Sci., 
ii,  XV:   95,  1853.     (Lignite  at  Brandon.)  — Virginia:   73.  Camp- 
bell, U.  S.  Geol.  Surv.,  Bull.  Ill,  1893.     (Big  Stone  Gap  field.) 
74.  Woodworth,  U.  S.  Geol.  Surv.,  22d  Ann.  Rept.,  Ill :  31,  1902. 
(Triassic  coal.)  —  Washington :  75.  Landes  and  Ruddy,  Wash.  Geol. 
Surv.,  II ;  Willis,  U.  S.  Geol.  Surv.,  18th  Ann.  Rept.,  Ill :  393,  1898. 
(Puget  Sound.)  —  West  Virginia :  76.  White,  West  Va.  Geol.  Surv., 
II:  1903.  —  Wyoming :  77.  Fisher,  U.  S.  Geol.  Surv.,  Bull.  225  :  345, 
1904.    78.  Knight,  Min.  Ind.,  Ill :  145,  1894. 


38  ECONOMIC   GEOLOGY   OF   THE   UNITED   STATES 


REFERENCES  ON  PEAT 

79.  Ries,  N".  Y.  State  Museum,  54th  Ann.  Kept.,  1903.  (N.  Y.,  Origin 
and  uses  in  general,  Bibliography.)  80.  Carter,  Ont.  Bur.  Mines, 
Kept,  for  1903.  (General.)  81.  Shaler,  U.  S.  Geol.  Surv.,  12th 
Ann.  Kept.,  p.  311.  (Peat  and  swamp  soils.)  82.  Roller,  Die 
Torfindustrie,  Vienna,  1889.  83.  Ries,  Min.  Res.,  U.  S.  Geol.  Surv., 
1901.  (U.  S.) 


CHAPTER   II 
PETROLEUM,  NATURAL  GAS,  AND   OTHER  HYDROCARBONS 

UNDER  this  head  are  included  a  number  of  hydrocarbon 
compounds,  of  complex  and  variable  composition,  ranging 
from  the  solid  to  the  gaseous  state,  the  series  including  four 
well-marked  and  well-known  members;  viz.,  natural  gas, 
petroleum,  mineral  tar  or  maltha,  and  asphalt.  The  de- 
velopment of  these  products,  and  especially  the  first  two, 
has  been  so  remarkable  and  attended  by  such  important 
economic  results  that  it  seems  well  to  preface  the  follow- 
ing description  by  a  brief  outline  of  this  history  of  their 
development. 

History  of  Petroleum  Development.  —  Petroleum  has  long 
been  known  in  many  parts  of  the  world  because  of  its  pres- 
ence in  bituminous  springs  or  as  a  floating  scum  on  the 
surface  of  pools.  It  was  used  at  an  early  date  on  the  walls 
of  Babylon  and  Nineveh,  and  was  obtained  by  the  Romans 
from  Sicily  for  use  in  their  lamps. 

In  the  United  States  petroleum  was  mentioned  by  French 
missionaries  even  in  1635,  and  the  early  Pennsylvania  settlers 
obtained  small  quantities  by  scooping  out  the  oil  from  dug 
wells.  Its  discovery  at  greater  depth  on  the  western  slope 
of  the  Alleghanies  was  made  during  the  drilling  of  brine 
wells;  but  its  early  use  was  chiefly  a  medicinal  one  until 
1863,  when  attempts  were  made  to  purify  it  for  use  as  a 

39 


40  ECONOMIC   GEOLOGY   OF   THE   UNITED   STATES 

lubricant  and  illurainant.  The  beginning  of  the  oil  industry 
is  usually  considered  to  date  from  the  sinking  of  a  successful 
well  by  Colonel  Drake  on  Oil  Creek,  Pennsylvania,  in  1860. 
From  this  center  prospectors  spread  out  in  all  directions  mak- 
ing valuable  discoveries,  until  now  petroleum  production  and 
refining  rank  among  the  leading  industries  of  the  country, 
the  supply  coming  from  many  states. 

History  of  Natural  Gras  Development.  —  Natural  gas  was 
discovered  and  first  employed  for  economic  purposes  at 
Fredonia,  New  York,  in  1821.  In  1841  it  was  used  in  the 
Great  Kanawah  Valley  _as  a  fuel  in  salt  furnaces,  but  its  first 
extensive  use  began  in  1872  at  Fairview,  Pennsylvania.  It 
was  used  in  1885  for  iron  smelting  at  Etna  Borough  near 
Pittsburg,  and  in  1886  was  piped  nineteen  miles  from 
Murrayville  to  Pittsburg.  Now  natural  gas  is  piped  long 
distances  to  cities,  being  used  as  a  fuel  in  many  industries, 
as  well  as  for  domestic  heating  and  lighting. 

Properties  of  Petroleum  (1,  2,  7).  —  Crude  petroleum  is  a 
liquid  of  complex  composition  and  variable  color  and  den- 
sity. It  consists  of  a  mixture  of  hydrocarbons,  the  American 
petroleum  belonging  usually  to  the  paraffin  series  although 
some  has  an  asphaltic  base.  The  Mississippi  River  forms 
a  rough  dividing  line  between  fields  containing  oil  with  a 
paraffin  base  and  those  with  an  asphaltic  base.  In  addition 
to  these  compounds,  petroleum  may  contain  substances  with 
a  small  percentage  of  nitrogen  and  sulphur. 

The  following  are  analyses  of  several  petroleums  from 
American  and  foreign  localities  :  — 


PETROLEUM,    NATURAL   GAS,    OTHER    HYDROCARBONS      41 
ELEMENTARY  ANALYSES  OF  PETROLEUMS 


PER  CENT 

SPECIFIC 

LOCALITY 

GRAVITY 

C. 

H. 

O. 

H2O  =  1 

Heavy  oil,  W.  Va  

83.5 

13.3 

3.2 

.873 

Light  oil,  W.  Va  

84.3 

14.1 

1.6 

.8412 

Heavy  oil  Pa 

84.9 

13.7 

1.04 

.886 

Light  oil,  Pa  

82.0 

14.8 

3.2 

.816 

Parma,  Italy  

84.0 

13.4 

1.8 

.786 

Hanover,  Germany       .     .     . 

80.4 

12.7 

6.9 

.892 

Galicia,  Austria  

82.2 

12.1 

5.7 

.870 

Light  oil,  Baku,  Rus.  .     .     . 

86.3 

13.6 

0.1 

.884 

Heavy  oil,  Baku,  Rus.      .     . 

86.6 

12.3 

1.1 

.938 

Java  

87.1 

12.0 

0.9 

.923 

Beaumont,  Texas    .... 

86.8 

13.2 

.920 

Petroleums  commonly  vary  in  specific  gravity  between 
.801  and  .965,  the  following  being  some  of  the  limits  shown 
by  American  oils :  — 

SPECIFIC  GRAVITY  OF  SOME  AMERICAN  PETROLEUMS 


STATE 

SPECIFIC  GRAVITY 

GRAVITY  BEAUME  1 

Pennsylvania     

.801-.817 

46.2-42.6 

Ohio 

816    860 

428-325 

Kansas      

.835-1.000 

38.8-10.0 

West  Virginia 

841    873 

37  6-30  0 

Beaumont,  Texas  

.904-.925 

24.8-31.1 

919    945 

23  3  119 

California     

.920-.983 

21.9-12.3 

The  temperature  at  which  crude  petroleum  solidifies  ranges 
from  82°  F.,  in  some  Burma  oils,  to  several  degrees  below 
zero  in  certain  Italian  oils.  The  flashing  point,  or  the  lowest 

1  A  specific  gravity  of  1,  compared  with  water,  is  10°  on  the  Beaume  scale. 


42 


ECONOMIC   GEOLOGY  OF   THE   UNITED  STATES 


temperature  at  which  inflammable  vapors  are  given  off, 
may  be  as  low  as  zero  degrees  in  the  Italian  oils  to  as  high 
as  370°  F.  in  an  oil  found  on  the  Gold  Coast  of  Africa,  but 
these  are  extreme  limits.  There  is  also  a  great  range  in  the 
boiling  point,  which  is  180°  F.  in  some  Pennsylvania  oils  and 
338°  F.  in  oils  found  at  Hanover,  Germany. 

The  various  liquid  hydrocarbons  making  up  crude  petro- 
leum vary  in  their  specific  gravity  and  boiling  point.  The 
more  important  oils  which  can  be  separated  from  crude  pe- 
troleum by  distillation  are  gasoline,  benzine,  heavy  naphthas, 
and  residuum.  Those  with  a  paraffin  base  are  generally 
lighter  and  more  valuable  on  account  of  the  higher  quantity 
and  quality  of  the  naphthas,  illuminating  oils,  and  lubricating 
oils  which  they  produce.  Those  with  an  asphalt  base  are  of 
inferior  quality  and  chiefly  valuable  for  fuel.  Their  trans- 
portation by  pipe  lines  is  also  more  difficult. 

The  percentage  of  the  different  distillates  varies. 

The  following  average  percentages  of  distillates  were 
yielded  by  the  oils  of  several  fields  in  1902  (Oliphant)  :  — 


APPALACHIAN 
FIELD 

LIMA,  IND. 
FIELD 

KANSAS 
FIELD 

Naphthas    .              .    . 

201 

10  9 

18 

Illuminating  oils  

61.4 

488 

30 

Lubricating  and  heavy  oils   .     . 

7.1 
63 

17.2 

25 

Loss  from  uncondensed  products 
and  water 

51 

230 

27 

Properties  of  Natural  Gas.  —  This  consists  chiefly  of  Marsh 
gas  —  fire  damp  —  CH4.  It  is  colorless,  odorless,  burns 
readily  with  a  luminous  flame,  and  when  mixed  with  air, 


PETROLEUM,   NATURAL  GAS,   OTHER   HYDROCARBONS     43 


it  is  highly  explosive.  As  is  shown  by  the  following  anal- 
yses, several  other  gases  are  commonly  present  in  small 
quantities  :  — 

ANALYSES  OF  NATURAL  GAS 


HYDRO- 
GEN 

MAKSH 
GAS 

OLEFI- 
ANT  GAS 

CAB- 

BOKIC 

OXIDE  / 

CAE- 
BON  DI- 
OXIDE 

OXYGEN 

NlTKO- 
GEN 

SUL- 

PHCBIO 

HYDRO- 
GEN 

Fostoria,  O. 

1.89 

92.84 

.20 

.55 

.20 

.35 

3.82 

.16 

Findlay,  0. 

1.64 

93.35 

.35 

.41 

.25 

.39 

3.41 

.20 

Muncie,  Ind. 

2.35 

92.67 

.25 

.45 

.25 

.35 

3.53 

.15 

Mode  of  Occurrence  (4,5,6,8).  —  Oil  is  rarely  found  without 
gas,  and  saline  water  is  likewise  often  present.  If  the  con- 
taining strata  are  horizontal,  the  oil  and  gas  are  usually 
irregularly  scattered,  but  if  tilted  or  folded,  they  collect  at 
the  highest  point  possible.  It  was  the  result  of  observa- 


a    GAS  .  b   OIL  0    WATER  d    CAPROCK 

FIG.  13.  —  Section  of  anticlinal  fold  showing  accumulation  of  gas,  oil,  and  water. 
After  Hayes,  U.  S.  Geol.  Surv.,  Bull.  212. 

tions  along  this  line  that  led  I.  C.  White  to  develop  what 
is  known  as  the  "  Anticlinal  Theory "  (8).  According  to 
this  theory,  in  folded  areas  the  gas  collects  at  the  summit 
of  the  fold,  with  the  oil  immediately  below,  on  either  side, 
followed  by  water  (Fig.  13).  Unless  there  are  secondary 


44  ECONOMIC   GEOLOGY   OF   THE   UNITED   STATES 

anticlines,  the  intervening  synclines  are  liable  to  be  barren 
of  oil  and  gas.  For  this  theory,  as  for  others,  it  is  necessary 
that  the  oil-bearing  stratum  shall  be  capped  by  a  practically 
impervious  one. 

Such  anticlinal  waves  are  found  in  the  oil  fields  of  the 
Appalachians,  Indiana,  western  Ohio,  and  many  other  locali- 
ties. While  this  theory  has  been  disputed,  it  may  be  con- 
sidered established  for  many  localities.  The  rival  theory 
advanced  by  Lesley  and  Ashburner,  that  the  oil  has  accumu- 
lated in  porous  areas  of  rock,  perhaps  ancient  shore-line 
deposits,  may  likewise  apply  in  some  cases.  It  supplies  all 
the  necessary  conditions  of  a  subterranean  reservoir  for  the 
accumulation  of  oil  in  "pools." 

In  the  first  discovered  fields,  the  oil  and  gas  were 
found  in  porous,  sandy  strata,  varying  from  fine-grained, 
cemented  sandstone  to  loose  gravels.  These  strata  were 
termed  sands,  and  the  area  of  porous  oil  sand  was  called 
the  pool.  Later  discoveries  in  Ohio  and  Indiana  showed 
that  the  gas  and  oil  might  occur  in  limestone  also. 

The  quantity  of  oil  which  a  cubic  foot  of  apparently  dense 
rock  can  hold  is  often  surprising.  White  (36)  estimated 
that  fairly  productive  sands  may  hold  from  six  to  twelve 
pints  of  oil  per  cubic  foot,  but  that  probably  not  more  than 
three-fourths  of  the  quantity  stored  in  the  rock  is  obtain- 
able. The  ease  with  which  the  containing  rock  yields  its 
supply  of  oil  depends  largely  on  the  openness  of  the  pores. 

Pressure  of  Oil  and  Gas  Wells.  —  Since  both  oil  and  gas 
usually  occur  in  the  earth  under  pressure,  any  break  in  the 
porous  rock  or  reservoir  which  contains  them  allows  them 
to  escape,  frequently  giving  rise  to  surface  indications,  and 
the  force  with  which  oil  and  gas  oftentimes  issue  from  a 


PETROLEUM,   NATURAL  GAS,   OTHER   HYDROCARBONS      45 

well  indicates  the  pressure  under  which  they  are  confined. 
It  is  sometimes  sufficient  to  blow  out  the  drilling  tools  and 
casing,  as  well  as  to  cause  the  oil  to  spout  many  feet  into 
the  air. 

There  are  several  remarkable  cases  of  the  amount  spouted  by  these 
gushing  wells.  One  of  these  is  the  famous  Lucas  well  at  Beaumont, 
Texas,  which  in  1901  for  nine  days  gushed  a  six-inch  stream  to  a  height 
of  160  feet,  at  the  rate  of  75,000  barrels  per  day.  This,  however,  is 
small  compared  with  the  records  of  some  Russian  oil  wells.  Although 
many  wells  flow  when  first  drilled,  this  does  not  usually  continue  long, 
and  the  oil  then  has  to  be  brought  to  the  surface  by  pumping.  The  depth 
of  the  wells  drilled  in  the  United  States  ranges  from  250  to  3700  feet, 
and  over  70  per  cent  of  the  total  number  drilled  are  located  in  Ohio 
and  Pennsylvania. 

The  maximum  pressure  which  a  well  develops  when  closed 
has  been  called  rock  pressure.  As  a  result  of  his  studies 
in  the  Ohio-Indiana  field,  Orton  (29)  found  that  the  rock 
pressure  was  the  same  as  that  of  a  column  of  water  whose 
height  was  equal  to  the  difference  in  elevation  between  the 
level  of  Lake  Erie  and  that  of  the  oil  or  gas  bearing  stratum. 
He  therefore  considered  it  to  be  hydrostatic  pressure.  This 
theory,  while  apparently  applicable  in  many  localities,  was 
found  to  be  inadequate  to  explain  the  great  pressure  shown 
in  many  shallow  wells.  In  such  cases,  no  doubt,  as  in  many 
others,  the  pressure  is  due  to  the  expansive  force  of  the 
imprisoned  gas. 

Either  the  drilling  of  additional  wells  or  a  drain  by  exces- 
sive use  from  wells  already  bored  commonly  causes  a  slow 
decrease  in  pressure  in  an  oil  or  gas  field.  Thus  in  the 
natural-gas  region  of  Findlay,  Ohio,  the  rock  pressure  in 
1885  was  450  pounds  per  square  inch;  400  in  1886;  360- 
380  in  1887;  250  in  1889;  170-200  in  1890.  Some  West 


46  ECONOMIC   GEOLOGY  OF   THE  UNITED   STATES 

Virginia  wells  have  shown  a  measured  rock  pressure  of 
1110  pounds  per  square  inch  and  an  estimated  pressure  of 
2000  pounds. 

Origin.  —  That  the  solid,  liquid,  and  gaseous  hydrocarbons 
are  more  or  less  closely  related  is  evident  from  the  fact  that 
the  gases  given  off  by  petroleum  are  similar  to  those  pre- 
dominating in  natural  gas,  while  the  exposure  of  many 
petroleums  to  the  air  results  in  a  change  to  a  viscous  mass 
and  finally  to  a  solid,  asphalt-like  substance.  It  is  a  well- 
known  fact  that  petroleum  is  rarely  free  from  natural  gas, 
although  this  gas  may  sometimes  form  alone,  as  in  coal 
mines,  or  from  decaying  vegetation  in  stagnant  pools.  The 
origin  of  the  hydrocarbon  compounds  has  been  the  subject 
of  much  speculation  among  both  chemists  and  geologists,  the 
former  for  a  time  arguing  for  an  inorganic  or  mineral  origin, 
the  latter  for  an  organic  derivation. 

Inorganic  Theory.  —  Several  theories  have  been  advanced 
to  account  for  an  inorganic  origin  of  oil,  the  most  important 
of  which,  though  not  the  earliest,  was  that  of  Mendeljeff, 
the  Russian  chemist.  According  to  his  theory,  the  interior 
of  the  earth  contains  metallic  iron,  as  well  as  carbid  of  iron 
like  that  found  in  meteorites.  Waters  percolating  down- 
ward through  the  earth's  crust,  on  reaching  the  heated 
interior,  become  converted  into  steam,  which,  attacking  the 
carbid  of  iron,  forms  hydrocarbons.  These  are  forced  to  the 
surface  by  the  expansive  force  of  the  steam. 

From  a  purely  chemical  standpoint,  this  theory  is  reason- 
able, but  it  does  not  accord  with  geologic  facts.  If  petro- 
leum were  found  in  this  manner,  we  should  expect  to  find  it 
widely  distributed  through  the  oldest  rocks  of  the  earth's 


PETROLEUM,    NATURAL   GAS,    OTHER   HYDROCARBONS      47 

crust.  On  the  contrary,  it  is  known  in  these  rocks  at  only 
one  locality,  in  Ontario,  where  a  hard,  compressed  asphalt 
is  found  in  crystalline  rocks.  It  is  significant  that  this 
material,  which  was  probably  originally  petroleum,  occurs 
in  rocks  which  show  evidence  of  having  been  originally 
stratified. 

Organic  Theory.  —  This  considers  that  petroleum  has  been 
derived  from  either  animal  or  vegetable  matter  by  a  process 
of  slow  distillation,  although  the  exact  changes  involved  are 
uncertain.  There  are  several  strong  arguments  in  favor  of 
it.  (1)  Petroleum  is  a  combustible  substance,  and  all  other 
similar  combustibles  have  originated  organically.  (2)  It  is 
possible  to  artificially  produce,  from  either  animal  or  vege- 
table substances,  both  gaseous  and  liquid  compounds  which 
are  closely  analogous  to  those  found  in  petroleum  and 
natural  gas.  Fish  oil,  for  example,  will  on  distillation  yield 
petroleum  compounds,  including  illuminating  oil,  lubricating 
oil,  benzine,  and  paraffin.  (3)  These  substances  occur  in 
fossil-bearing  rocks.  (4)  They  are  practically  absent  from 
the  crystalline  rocks.  (5)  In  some  places  these  substances 
occur  in  close  proximity  to  fossils.  (6)  Natural  gas  is 
actually  generated  in  coal  seams. 

Some  geologists,  including  Orton  (4)  and  Newberry  (Ohio 
State  Agric.  Rep.  1859),  have  believed  that  the  formation  of 
petroleum  has  taken  place  at  low  temperatures ;  but  others, 
including  Peckam  (6),  have  considered  heat  necessary.  In 
the  case  of  Appalachian  oils,  the  folding  of  the  strata  is  sup- 
posed to  have  supplied  this  heat. 

It  seems  doubtful  whether  either  petroleum  or  natural  gas 
have  migrated  any  great  distance  through  the  strata  subse- 
quent to  their  formation.  When  any  movement  has  taken 


48  ECONOMIC   GEOLOGY   OP   THE   UNITED   STATES 

place  through  pores  of  the  rock,  it  has  probably  been  due  to 
gravity  separation,  the  gas  rising  to  the  highest  point  of  the 
stratum  while  the  oil  settles. 

Geological  Distribution  of  Petroleum  and  Natural  Gas.  — 
Petroleum  is  widely  distributed  geologically,  being  found  in 
rocks  whose  age  ranges  from  the  Ordovician  to  the  most 
recent,  the  occurrences  in  Paleozoic  strata  being  chiefly  in 
eastern  United  States,  those  in  post-Carboniferous  strata  in 
the  western  and  southern  states. 

Natural  gas  may  show  an  equally  wide  geological  distribu- 
tion, although  in  the  United  States  the  larger  amount  is  now 
obtained  from  the  Paleozoic  formations. 

Distribution  of  Petroleum  in  the  United  States.  —  The  im- 
portant petroleum  occurrences  of  the  United  States,  so  far  as 
at  present  known,  may  be  considered  to  belong  to  the  seven 
following  fields  (Fig.  14) :  (1)  the  Appalachian  field,  includ- 
ing New  York,  western  Pennsylvania,  eastern  Ohio,  West 
Virginia,  Kentucky,  and  Tennessee;  (2)  the  Ohio-Indiana 
field ;  (3)  the  Texas-Louisiana  field ;  (4)  the  Kansas-Indian 
Territory  field ;  (5)  the  Colorado  fields ;  (6)  the  Wyoming 
fields;  (7)  the  California  fields.  In  addition  to  these  there  are 
scattered  occurrences  in  Michigan,  etc.  (See  map,  Fig.  14.) 

Appalachian  Field.  —  This  field,  which  supplied  over  85  per 
cent  of  the  oil  produced  in  the  United  States  in  1902,  extends 
from  southwestern  New  York  (25)  into  West  Virginia  (37,  38) 
and  is  subdivided  into  several  districts,  each  containing  sev- 
eral "pools."  The  region  is  of  interest  historically  and  geo- 
logically, some  of  the  earliest  discoveries  of  oil  having  been 
made  in  it.  The  oil  is  obtained  from  sandstones  and  con- 
glomerates, ranging  in  age  from  the  Upper  Carboniferous 


PLATE  III 


FIG.  1.  —  General  view  of  Tuna  Valley,  in  Pennsylvania  oil  field.    Photo,  by  F.  H. 
Oliphant. 


FIG.  2.  —  View  in  Los  Angeles,  Calif.,  oil  field.    Such  close  spacing  of  oil  derricks 
tends  to  hasten  the  exhaustion  of  the  oil  supply. 


PETROLEUM,    NATURAL   GAS,    OTHER    HYDROCARBONS      49 


in  the  upper  part  of  the  field,  to  Middle  Devonian  in  the 
lower  portion,  which  underlie  an  area  of  probably  55,000 


square  miles.     There  are  often  several  productive  beds  in  a 
single  formation,  and  40  oil  sands  have  been  recognized  in 


50 


ECONOMIC    GEOLOGY   OF   THE   UNITED    STATES 


the  entire  section.  This  field,  which  is  the  most  important 
in  the  United  States,  supplies  a  large  amount  of  high-grade 
petroleum,  and  has  a  large  output ;  but  apparently  the  pro- 
duction has  practically  reached  its  maximum.  The  petroleum- 
producing  areas  of  Pennsylvania  (31,  32)  are  divided  into  a 
number  of  districts,  this  division  being  based  partly  on  quality 
and  partly  on  county  lines.  Each  district  may  be  subdivided 
into  pools.  In  the  Clarendon  and  Warren  County  district 
is  found  some  of  the  finest  petroleum  produced  in  the  United 


TRENTON 

LIMESTONE 


UTICA 

SHALE 


HUDSON  R.      NIAGARA  LIMESTONE  LOWER  UPPER  OHIO 

SHALE  NIAGARA  SHALE          HELDERBERO  HELDERBERQ  SHALE 

MEDINA          CLINTON  LIMESTONE       LIMESTONE  LIMESTONE 


FIG.  15.  —  Geological  section  of  Ohio-Indiana  oil  and  gas  fields.    After  Orton. 
U.S.  Geol.  Surv.,  8th  Ann.  Rept.,  II. 

States,  while  the  Franklin  district  is  noted  for  the  fine,  natu- 
ral lubricating  oil  which  it  yields.  In  Kentucky  (22)  and 
Tennessee  a  limited  amount  of  petroleum  is  obtained  from 
Silurian  rocks.  The  total  number  of  wells  drilled  in  the 
Appalachian  field  from  1877  to  the  end  of  1903  was  137,679. 
Ohio-Indiana  Field  (16-18,  26-30). — The  discovery  of  oil 
and  gas  in  the  Trenton  rocks  of  western  Ohio  in  1884  caused 
considerable  excitement,  since  it  showed  the  existence  of 
petroleum  in  limestone,  an  exception  to  previously  known 
conditions,  and  at  a  much  lower  geological  horizon  than  any 
in  which  oil  or  gas  had  hitherto  been  found.  This  field 


PLATE  IV 


PETROLEUM,   NATURAL   GAS,    OTHER    HYDROCARBONS      51 


extends  from  Findlay  in  northwestern  Ohio  south  westward 
into  Indiana.  The  oil,  which  is  dark  and  heavy,  and  con- 
tains a  higher  percentage  of  sulphur  than  the  Pennsylvania 
oil,  is  found  near  the  top  of  the  porous,  dolomitized  portions 
of  the  Trenton  limestones,  at  depths  of  about  1100  feet. 
The  limestone,  which  shows  several  low  folds  (Fig.  15),  is 
covered  by  the  impervious  Hudson  River  shales. 

Texas- Louisiana  Oil  Fields  (33-35).  —  These  occur  in  a  belt 
from  50  to  75  miles  wide  along  the  Gulf  Coast  from  near  the 
Mississippi  River  in  Louisiana  to  a  point  about  two  thirds 
the  way  across  Texas  (Fig.  14).  The  nearly  flat  surface  of 
this  coastal  plain 
is  occasionally  in- 
terrupted by  low 
mounds  or  swells 
which  seem  to  in- 
dicate favorable 
conditions  for  the 
accumulation  of  oil 
below  the  surface. 
Underlying  this 
area  is  a  series  of 


FIG.  16.  —  Section  of  Spindle  Top  oil  field  near  Beau- 
mont, Texas.   After  Fenneman,  Min.  Mag.,  XI:  317. 


Quaternary  and  Tertiary  clays,  sands,  and  gravels,  with 
occasional  limestones,  having  in  general  a  gentle  southeast- 
ern dip  interrupted  by  low  domes. 

The  oil  pools  are  all  of  small  size,  that  at  Beaumont,  which 
is  the  best  known,  covering  an  area  of  about  200  acres 
(PI.  IV).  It  was  discovered  in  1901,  and  within  a  year 
and  a  half  280  successful  wells  had  been  drilled.  The  oil 
rock,  which  lies  from  900  to  1000  feet  below  the  surface,  is 
a  very  porous,  crystalline  dolomitic  limestone,  and  the  cap- 


52  ECONOMIC   GEOLOGY   OF   THE   UNITED   STATES 

rock  is  clay.  The  occurrence  of  gypsum  and  salt  under- 
lying the  oil  rock  in  some  of  the  wells  is  unique  (Fig.  16). 
Many  of  the  wells  in  this  pool  were  gushers,  but  so  great  was 
the  drain  on  this  field  that  by  the  end  of  the  first  year  after 
its  discovery  the  pressure  was  considerably  reduced,  and  in 
1903  many  of  the  wells  had  practically  ceased  producing, 
while  others  were  yielding  a  mixture  of  salt  water  and  oil. 
The  production,  however,  is  still  considerable,  although  the 
supply  is  no  doubt  exhaustible.  The  coastal-plain  oils  have 
an  asphaltic  base,  or  are  "heavy,"  and  at  times  contain  con- 
siderable sulphur. 

In  1903  many  wells  were  being  developed  in  the  Sour  Lake  district 
about  20  miles  northwest  of  Beaumont.  The  oil  is  heavy  like  that  of 
Beaumont,  but  runs  lower  in  sulphur.  In  Louisiana  active  drilling 
operations  have  been  carried  on  in  the  region  around  Jennings,  and  one 
well  yielded  20,000  barrels  per  day  while  it  was  gushing.  The  oil  re- 
sembles that  of  Beaumont. 

The  belt  of  Cretaceous  rocks  of  central  Texas  has  yielded  both  oil  and 
gas  at  several  localities,  but  the  only  important  one  is  at  Corsicana,  where 
both  a  light  and  heavy  oil  have  been  found  in  sands  interbedded  with 
dense  clay  shales.  The  two  kinds  of  oil  occur  at  different  horizons. 

Kansas  (19-21).  —  In  southeastern  Kansas  a  dark  green 
oil  is  obtained  from  the  sugar  sands  near  the  bottom  of  the 
Cherokee  shales,  about  800  feet  below  the  surface.  A  second 
horizon  is  found  about  300  feet  lower. 

California.  —  There  are  a  number  of  productive  fields  in 
California  (10-12),  all  lying  south  of  the  latitude  of  San  Fran- 
cisco. Altogether  there  are  10  or  12  horizons  in  the  folded 
Tertiary  strata,  which  have  a  total  thickness  of  20,000  feet. 
The  oil  which  is  found  in  conglomerates,  sandstones,  and 
arenaceous  shales,  is,  in  the  most  productive  areas,  found 
closely  associated  with  anticlines,  but  the  strata  are  in  many 


PETROLEUM,    NATURAL   GAS,    OTHER    HYDROCARBONS      53 


FIEXURE         OILSAN 


FIG.  17.  — Section  in  Los  Angeles  oil  field. 
After  Watts,  Calif.  State  Min.  Bureau, 
Bull.  11 :  7,  1897. 


places  extensively  faulted  (Fig.  17),  and  it  is  doubtless  to 
these  faults  that  many  of  the  California  oil  springs  are  due. 
By  adding  to  the  porosity  of  the  rocks,  the  faulting  has 
probably  also  increased  the  capacity  of  some  of  the  oil 
reservoirs. 

In  1903  the  Kern  River  field  was  the  most  productive 
in  California.  It  has  an  area  of  12  square  miles,  the  oil 
being  found  at  depths 
ranging  from  200  to  300 
feet  in  a  series  of  lower 
Miocene  sands  inter- 
bedded  with  clay.  The 
wells  yield  from  a  few 
barrels  up  to  600  per 
day,  but  are  flowing  usually  for  only  a  short  period. 

The  California  oils,  like  those  of  Texas,  have  an  asphaltic 
base,  those  found  in  the  shale  being  generally  lighter. 

Wyoming  (39-41). — This  state  contains  18  oil  districts, 
most  of  which  are  but  slightly  developed  and  the  geology 
imperfectly  known.  Most  of  them  are  in  the  Mesozoic 
strata,  the  balance  in  Upper  Carboniferous,  the  oil  being 
commonly  found  along  the  axes  of  anticlinal  folds.  The 
wells  vary  from  300  to  1500  feet  in  depth,  and  the  oils 
are  mostly  lubricating,  although  a  few  contain  considerable 
kerosene  (39). 

Colorado. — The  oil  at  Florence  (13,  15),  in  this  state,  is 
found  in  porous,  sandy  layers  of  Cretaceous  age,  at  depths 
of  from  1000  to  2000  feet,  and,  unlike  most  other  occur- 
rences, in  a  synclinal  trough.  It  is  a  heavy  oil.  Near 
Boulder  (14)  there  is  another  oil  field,  recently  developed, 
in  which  the  oil  is  found  at  depths  as  great  as  3400  feet. 


54      ECONOMIC  GEOLOGY  OF  THE  UNITED  STATES 

Alaska.  —  Petroleum  has  been  found  at  several  localities 
in  Alaska  (Fig.  81),  and  the  developmental  work  already 
done  gives  promise  of  a  supply  in  the  future  (9,10). 

Distribution  of  Natural  Gas  in  the  United  States. —  The 

distribution  of  natural  gas  is  almost  coextensive  with  that 
of  petroleum,  but  the  commercially  important  fields  are 
fewer  in  number.  The  most  important  producing  states  are 
New  York  (51),  Pennsylvania  (54),  Ohio  (53),  Indiana  (45), 
and  Kansas  (47). 

New  York.  —  Gas  is  found  in  several  formations,  includ- 
ing the  Medina  and  Oswego  sandstones,  Utica  shale,  and 
Potsdam  sandstone,  but  the  main  supply  is  distributed 
through  the  Devonic  sandstones  of  southwestern  New  York. 
A  large  field  in  Erie  County  obtains  its  supply  from  the 
Medina  sandstone,  some  of  the  wells  having  yielded  as  high 
as  1,000,000  cubic  feet  daily.  In  Onondaga  County  gas  is 
found  in  the  Trenton  limestone. 

Pennsylvania.  —  Gas  is  obtained  from  the  same  forma- 
tions that  carry  the  oil.  The  Bradford  district  was  the 
first  developed,  and  formerly  yielded  gas  of  high  pressure. 
Much  is  still  obtained  from  McKean,  Elk,  and  Warren 
counties.  Extensive  deposits  were  also  found  about  Pitts- 
burg,  and  later  to  the  south  of  it.  Green  and  Washington 
counties  now  produce  important  supplies  from  a  pool  whose 
length  is  about  25  miles  and  width  3  to  4  miles,  with  pres- 
sure ranging  from  800  to  1000  pounds.  Although  in  recent 
years  several  new  gas-bearing  sands  have  been  discovered 
in  southwestern  Pennsylvania,  the  enormous  demand  for 
the  gas  threatens  exhaustion  of  the  available  supply  at  no 
very  distant  date. 


PETROLEUM,    NATURAL   GAS,    OTHER    HYDROCARBONS      55 

West  Virginia  (see  Petroleum  references).  —  This  state 
is  now  the  leading  producer  of  natural  gas  in  the  United 
States,  and  is  looked  to  as  an  important  source  of  future 
supply  for  both  Ohio  and  Pennsylvania,  whose  gas  supply 
is  slowly  falling  off.  The  main  supply  is  obtained  from 
the  Gordon  and  Fifth  sands  of  the  Catskill  formation, 
this  being  a  higher  horizon  than  that  yielding  the  gas  in 
the  Bradford  district  of  Pennsylvania.  Immense  quantities 
are  obtained  from  the  fields 'of  Wetzel  and  Tyler  counties, 
the  wells  being  from  2700  to  3200  feet  deep.  Pipe  lines 
are  now  run  from  this  district  to  Pittsburg,  and  a  line 
has  been  laid  from  Tyler  County  to  Cleveland,  Ohio.  Un- 
fortunately, by  allowing  it  to  escape  with  the  petroleum, 
many  thousand  cubic  feet  of  gas  have  been  wasted  in  this 
state. 

Ohio  (52-53). — The  Trenton  limestone,  which  formerly 
supplied  large  quantities  of  natural  gas,  is  now  so  nearly 
exhausted  that  little  gas  is  obtained  except  by  pumping. 
Some  gas  is  obtained  from  the  Clinton  sandstone  of  central 
and  eastern  Ohio,  and  small  amounts  from  the  Corniferous 
limestone ;  but  many  towns  in  this  state  are  now  supplied 
by  the  West  Virginia  fields. 

Indiana  (45,46).  —  The  gas  fields  of  this  state,  covering 
about  2500  square  miles,  were  formerly  among  the  most 
important  in  the  country,  the  gas  being  obtained  from  the 
Trenton  limestone.  The  supply  is,  however,  rapidly  giving 
out,  and  its  complete  exhaustion  is  probable  at  no  very 
distant  date. 

Kansas  (47-50). — Southeastern  Kansas  and  northern  Indian 
Territory  are  underlain  by  what  is  probably  an  extensive 
sandstone  gas  field.  The  supply  comes  from  the  Cherokee 


56  ECONOMIC    GEOLOGY   OF   THE    UNITED    STATES 

shale,  and  is  now  much  used  as  a  source  of  fuel  in  the  local 
metallurgical  and  manufacturing  industries. 

Some  gas  is  obtained  from  eastern  Kentucky.  Scattered 
pockets  of  high-pressure  gas  have  also  been  found  at  several 
localities  in  Texas  and  also  in  California. 

Uses  of  Petroleum.  —  The  three  most  important  uses  are 
for  light,  heat,  and  lubrication ;  but  the  various  distillates 
have  special  uses.  Rhigolene  is  used  as  a  local  anaesthetic, 
gasoline  is  used  as  a  fuel,  and  naphtha  as  a  solvent  for 
resins  in  making  varnish  and  in  oilcloth  manufacture,  while 
benzine  is  of  value  for  cleaning  and  as  a  substitute  for 
and  an  adulterant  of  turpentine.  Astral  oil  and  mineral 
sperm  oil  are  special  grades  of  illuminating  oil  with  high 
flashing  points.  Crude  petroleum  is  now  much  used  for 
fuel  purposes  in  engines,  as  along  the  Pacific  coast  and 
in  the  southwest,  where  good  coal  is  so  scarce  that  many  of 
the  locomotives  are  run  by  the  use  of  crude  oil. 

The  paraffin  residue  is  placed  on  the  market  for  medicinal 
purposes  under  the  name  of  vaseline,  petroleum  ointment, 
and  cosmoline.  It  is  also  used  as  an  adulterant  of  candy 
and  for  electrical  insulation. 

Uses  of  Natural  Gas.  —  Natural  gas  is  widely  employed 
as  a  fuel  in  factories,  metallurgical  establishments,  glass 
works,  cement  plants,  etc.  For  domestic  purposes,  such  as 
heating,  cooking,  and  lighting,  it  is  also  widely  used.  Its 
cheapness,  cleanliness,  and  high  calorific  power,  and  the 
ease  with  which  it  can  be  used  have  been  important  factors 
in  insuring  its  widespread  selection  for  the  above  purposes. 

Oil  Shales  (55  a  and  b) .  —  Shale  containing  sufficient  petro- 
leum to  permit  its  extraction  by  a  process  of  distillation  is 


PETROLEUM,   NATURAL  GAS,   OTHER   HYDROCARBONS      57 

known  as  torbanite  or  kerosene  shale.  Such  shales  are  found 
in  the  Carboniferous  of  New  South  Wales,  Australia,  New 
Zealand,  and  Scotland,  and  in  the  Cretaceous  of  Brazil. 
They  are  almost  unknown  in  the  United  States.  The  fol- 
lowing analysis  indicates  the  composition  and  richness  of 
shale  in  hydrocarbons  :  — 


MOIST 

VOLATILE 
HYDRO- 
CARBON 

FIXED 
CARBON 

ASH 

SULPHUR 

Rich  shale,  Joadja,  N.S.W.  . 

.16 

89.59 

5.27 

4.96 

.384 

The  oil  can  be  obtained  by  distillation  in  retorts;  but  in  view  of 
the  large  available  supplies  of  petroleum,  obtainable  in  many  parts 
of  the  world,  the  material  at  present  has  but  little  commercial  value. 
It  is  distilled  in  New  South  Wales  and  also  in  Scotland. 


SOLID  BITUMENS 

Occurrence  (56-60,  66).  —  Solid  bitumens  may  be  grouped 
according  to  their  mode  of  occurrence,  as  (1)  asphaltites, 
which  represent  the  varieties  free  from  sandy  and  clayey 
impurities,  found  filling  either  fissures  or  basins  ;  (2)  bitu- 
minous rocks,  in  which  the  bitumen  fills  the  pores  of  sand- 
stones, limestones,  or  other  rocks.  They  are  found  over  a 
wide  range  (Fig.  18),  both  geographically  and  geologically. 

A  study  of  the  deposits  leads  to  the  conclusion  that  these 
solid  bituminous  compounds  have  been  derived  from  petro- 
leum (58,  59,  60),  for  the  following  reasons :  In  the  asphal- 
tite  deposits  the  solid  bitumens  are  often  associated  with 
petroleum  springs,  or  with  fissures  leading  down  to  or 
toward  petroleum-bearing  strata.  In  some  cases  the  asphal- 
tite  not  only  fills  such  a  fissure,  but  impregnates  the  wall 


58     ECONOMIC  GEOLOGY  OP  THE  UNITED  STATES 

rock  to  a  distance  of  a  foot  or  two  on '  either  side  of  the 
vein,  indicating  that  the  material  came  up  through  the 
fissure  in  a  liquid  condition,  filling  it,  and  even  penetrating 
the  wall  rock. 

The  bitumen  in  bituminous  rocks  may  either  have  origi- 
nated from  organic  remains  within  the  rock  itself  or  have 
seeped  into  it  from  some  neighboring  pool.  In  either  case 
the  material  seems  originally  to  have  been  liquid  petroleum 
which  later  solidified. 


FIG.  18.  —  Map  of  asphalt  and  bituminous  rock  deposits  of  United  States.    After 
Eldridge,  U.  S.  Geol.  Surv.,  22d  Ann.  Kept.,  IX. 


Asphaltites.  —  There  are  several  varieties  of  asphaltites, 
all  black  or  dark  brown  in  color,  commonly  with  a  pitchy 
odor,  burning  readily  with  a  smoky  flame,  and  insoluble  in 
water,  but  soluble  in  ether,  oil  of  turpentine,  and  naphtha. 
Their  specific  gravity  ranges  from  1  to  1.1.  They  are 


PETROLEUM,   NATURAL  GAS,   OTHER   HYDROCARBONS      59 

closely  related  chemically  and  in  their  mode  of  occurrence, 
but  differ  somewhat  in  their  behavior  toward  solvents,  as 
well  as  in  their  fusibility.  The  most  important  varieties 
are  described  below. 

Albertite  (61),  a  black  bitumen  with  a  brilliant  luster  and  conchoidal 
fracture,  a  hardness  of  1  to  2  and  specific  gravity  1.097,  is  found  filling 
fissures  in  bituminous  shales  in  New  Brunswick. 

Anthraxolite  (63)  is  a  coaly,  lustrous,  black  mineral,  with  a  hardness 
of  3  to  4,  and  specific  gravity  of  1.965.  It  is  found  at  Sudbury,  Ontario, 
forming  veins  in  a  black  fissile  slate,  but  has  also  been  described  from 
other  localities. 

Ozokerite  (67),  also  termed  mineral  wax  or  native  paraffin,  is  a  waxlike 
hydrocarbon,  yellow  brown  to  green,  translucent  when  pure,  and  of 
greasy  feel.  Its  specific  gravity  is  .955.  While  known  to  occur  in  Utah, 
the  most  important  deposit  is  in  Galicia.  At  the  latter  locality  the 
Ozokerite  is  found  forming  veins  from  a  few  millimeters  up  to  several 
feet  in  thickness  in  much-disturbed  Miocene  shales  and  sandstones. 

Grahamite  (66)  is  a  vein  asphalt  found  in  the  Carboniferous  of  West 
Virginia. 

Lake  Asphalt  (71)  is  not  found  in  the  United  States,  but  occurs  in  the 
famous  pit  or  lake  on  the  island  of  Trinidad,  off  the  coast  of  Venezuela. 

Uintaite,  or  Gilsonite  (66),  is  a  black,  brilliant 
bitumen,  with  conchoidal  fracture,  hardness  2  to 
2.5,  and  specific  gravity  of  1.065  to  1.07.  It  is 
found  filling  a  series  of  fissures,  termed  veins,  in 
the  Bridger  beds  of  the  Tertiary  in  eastern  Utah, 
and,  to  a  less  extent,  in  western  Colorado.  One 
of  these  veins,  the  Duchesne,  has  been  worked  to 
a  depth  of  105  feet,  and  is  traceable  for  about  a 
mile,  its  width  for  half  this  distance  being  3  to  4 
feet.  It  is  usually  vertical  and  in  places  faulted. 

Manjak  is   the   name    applied    to    a    bitumen 

Fm.l9.-SectionofGil- 
resembhng    Lintaite,    found    on    the    island    of       sonite    vein,    Utah. 

Barbados.     It  is  a  hydrocarbon  of  high  purity,       After  Eldridge,  U.S. 

J         Geol.     Surv.,     VJth 
black  color,  brilliant  luster,  and  conchoidal  frac-       Ann.  Sept.,  I:  932. 


60 


ECONOMIC   GEOLOGY   OF  THE   UNITED   STATES 


ture,  and  forms  seams  from  a  quarter  of  an  inch  to  30  feet  thick  in 
a  blue  shale.     The  material  brings  $60  a  short  ton  in  New  York. 

Bituminous  Rocks  (66).  —  These  are  commonly  classified 
according  to  the  character  of  the  containing  rock,  as  bitu- 
minous sandstones,  bituminous  limestones,  and  bituminous 
schists.  They  are  much  more  widely  distributed  than  the 
asphaltites,  being  found  in  several  geological  horizons,  and 
are  worked  in  Kentucky  (66),  Indian  Territory  (66),  and 
California  (64). 

As  illustrative  of  its  mode  of  occurrence,  we  may  men- 
tion the  bituminous  sandstone,  which  is  extensively  quar- 
ried near  Santa  Cruz,  California  (PI.  V,  Fig.  1).  The 
rock,  which  is  of  blackish  or  brownish-black  color,  weather- 
ing to  gray,  occurs  beneath  the  Monterey  shales,  sometimes 
resting  directly  on  granites.  The  bitumen  impregnates 
the  heavy  bedded  sandstone  immediately  under  the  shale, 
and  also  the  sand  that  fills  cracks  which  extend  up  into 
the  shale.  These  cracks,  which  vary  in  width  from  very 
minute  size  up  to  25  or  30  feet,  are  sometimes  traceable 
for  several  hundred  feet,  being  at  times  of  value  as  guides 
in  finding  the  main  bed. 

Analyses.  —  The  variable  composition  of  asphaltites  and 
bituminous  rocks  can  be  seen  from  the  following  table :  — 

ANALYSES  OP  ASPHALTITES  AND  MALTHA 


LOCALITY 

SOLUBLE  IK 
CS2 

MINERAL 
MATTERS 

NON-BITUMINOUS 
ORGANIC  MATTER 

Trinidad  Lake  Asphalt  . 

54.25 

36.51 

9.24 

Grahamite,  W.  Va.    .    . 

100.00 





Gilsonite,  Utah     .    ,'  . 

100.00 

.10 



Maltha,  Kern.  Co.,  Calif. 

93.20 

5.77 

.54 

PLATE  V 


FIG.  1.  —  Quarry  of  bituminous  sandstone,  Santa  Cruz,  Calif.    After  Eldridge,  U.S. 
Geol.  Surv.,  22d  Ann.  Sept.,  I. 


FIG.  2.  — Granite  quarry,  Hardwick,  Vt.    Photo,  by  G.  H.  Perkins. 


PETROLEUM,   NATURAL   GAS,   OTHER   HYDROCARBONS      61 
ANALYSES  OF  BITUMINOUS  ROCKS 


LOCALITY 

MOISTURB 

SOLUBLE 
iNCSa 

CaC08 

MgCO, 

SAND  OB 
CLAY 

California   

2.50 

2020 

3.00 

7400 

576 

9422 

Seyssel,  France    .     .     . 



8.15 

91.70 



Limmer,  Germany  .     . 



18.26 

56.50 

27.01 

4.98 

Uses.  —  Trinidad  asphalt  mixed  with  powdered  rock  and 
tar  is  much  in  use  for  pavements,  and  the  bituminous  rocks 
are  employed  for  similar  purposes.  Ozokerite,  known  as 
Ceresin  in  its  purified  form,  is  used  in  the  manufacture  of 
candles,  ointments,  powders,  as  an  adulterant  of  bees- 
wax, and  for  bottles  to  hold  hydrofluoric  acid. 

The  most  important  use  of  Uintaite  and  Manjak  is  for 
making  low-grade  and  dipping  varnishes,  such  as  are  used 
for  iron  work  and  baking  Japans.  Other  uses  to  which 
the  Uintaite  at  least  has  been  put  are  for  preventing  elec- 
trolytic action  on  iron  plates  of  ship  bottoms,  coating 
masonry,  acid-proof  lining  for  chemical  tanks,  roofing  pitch, 
insulating  electric  wires,  as  a  substitute  for  rubber  in  com- 
mon garden  hose,  and  as  a  binder  pitch  in  making  coal 
briquettes. 

Production  of  Petroleum,  Natural  Gas,  and  Asphaltum.  — 
The  production  of  crude  petroleum  and  natural  gas  for 
several  years  is  given  below :  — 


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PETROLEUM,   NATURAL   GAS,   OTHER   HYDROCARBONS      63 
VALUE  OF  PETROLEUM  AND  XATURAL  GAS  PRODUCED  IN  1903 


STATE 

VALUE  OF 
PETROLEUM 

VALUE  OF 
NATURAL  GAS 

COMBINED 
VALUE 

Pennsylvania      .    .     . 
Ohio      
West  Virginia     .     .     . 
Indiana      

$18,170,881 
26,234,521 
20,516,532 
10,474,127 

$16,182,834 
4,479,040 
6,882,359 
6  098,364 

$34,353,715 
30,713,561 
27,398,891 
16,572,491 

7  399  349  • 

104  591 

7  503  870 

Texas     

7  517  479 

21  351 

7  538  830 

New  York  

1,849,135 

493  686 

2  342,821 

Other  states    .... 

2,532,026 

1,553,205 

4,085,231 

Total  

$94,694,050 

$35,815,360 

$130,509,410 

The  average  price  per  barrel  of  petroleum  naturally 
varies  somewhat  from  year  to  year.  In  1885  it  was  87-|^;  in 
1890,  86f^;  in  1895,  $1.36f ;  in  1900,11.194;  in  1903,  94j£ 

The  total  number  of  barrels  of  petroleum  produced  in  the 
United  States  from  1859  to  the  end  of  1903  was  1,265,751,585, 
while  the  total  value  of  the  natural  gas  produced  in  the 
United  States  from  1885  to  the  end  of  1903  was  1322,872,792. 

The  world's  production  of  petroleum  in  1902  and  1903 
was  as  follows :  — 

WORLD'S  PRODUCTION  OF  PETROLEUM  IN  1902  AND  1903 


COUNTRY 

BARRELS,  1902 

BARRELS,  1903 

United  States     
Russia  

69,389,194 
85,168,556 

100,461,337 
75,591,256 

3  038  700 

6  640  000 

3  251  544 

5,234,475 

Roumania      

1  406,160 

2,763,117 

1  430  716 

9  510  259 

1  100  000 

964,000 

Canada      

572  500 

481,504 

Germany   

313,630 

445,818 

Peru 

79961 

61,745 

Italy      .     .                       ...... 

10  100 

20,000 

All  other  countries     

20,000 

30,000 

Total 

165  773  361 

195,203,511 

64  ECONOMIC    GEOLOGY   OF   THE   UNITED   STATES 

EXPORTS  OF  MINERAL  OILS 


KIND 

1895 

1900 

1902 

1903 

Crude  

$5,161,710 

$7,340,749 

$6,331,011 

$6,782,136 

Naphtha  .... 
Illuminating      .     . 
Lubricating  and 
Paraffin      .     .     . 
Residuum     .     .     . 

910,988 
34,706,844 

5,867,477 
13,063 

1,681,201 
54,692,872 

9,933,548 
845,337 

1,392,771 
49,079,055 

10,872,154 
922,152 

1,518,541 
51,355,668 

12,690,065 
282,129 

Total      .     .     . 

$46,660,082 

$74,493,707 

$68,597,143 

$72,628,539 

The  petroleums  reach  a  wider  market  than  any  of  our 
other  exports,  and  over  38  per  cent  of  the  total  quantity  of 
crude  oil  produced  is  now  exported  in  either  crude  or  re- 
fined form.  This  was  formerly  sent  away  in  cans,  but  it  is 
now  transported  largely  in  bulk  in  tank  steamers,  some  of 
which  have  a  capacity  of  60,000  barrels.  (8  a) 

The  following  table  gives  the  production  of  the  different 
kinds  of  asphaltum  for  the  last  three  years :  — 

PRODUCTION  OF  ASPHALTUM  IN  THE  UNITED  STATES  FROM  1901-1903 


1901 

1902 

1903 

VARIETY 

SHORT 
TONS 

VALUE 

SHORT 
TONS 

VALUE 

SHORT 
TONS 

VALUE 

Bituminous  sandstone 

34,248 

$138,601 

57,837 

$156,993 

38,633 

$118,001 

Bituminous  limestone 

6,970 

33,375 

2,869 

19,817 

2,520 

8,800 

Mastic  

961 

11,532 

Hard  and  refined   or 

Sfum  . 

19,316 

333  509 

22321 

264  817 

1°  896 

343  799 

Liquid  or  maltha   .     . 

2,600 

49,850 

1,605 

20,172 

58 

1,150 

PETROLEUM,    NATURAL   GAS,    OTHER    HYDROCARBONS      65 

The  production  by  states  in  1903  was  as  follows :  — 


STATE 

QUANTITY 
SHORT  TONS 

VALUE 

California     

74,578 

$  702,758 

Texas 

2  158 

30550 

Utah    

5,619 

188,357 

12578 

50  163 

Indian  Territory  

5,107 

28,150 

1215 

5468 

Since  deposits  of  the  purer  type,  such  as  lake  asphalt, 
are  very  scarce  in  the  United  States,  the  supply  for  domes- 
tic consumption  is  obtained  from  foreign  countries.     The 
imports  for  the  last  two  years  are  given  below :  — 
IMPORTS  OP  ASPHALTUM 


19 

02 

19 

03 

LONG  TONS 

VALUE 

LONG  TONS 

VALUE 

West  Indies 

106  844 

$358316 

139  031 

$415291 

Venezuela  

12,406 

62028 

16,445 

74874 

All  others 

375 

8533 

17416 

95770 

Total       .... 

119625 

$  428  877 

17°  892 

$  585  865 

The  world's  production  for  1902  was  as  follows : 
WORLD'S  PRODUCTION  OF  ASPHALTUM  IN  1902 


COUNTRY 

SHORT  TONS 

VALUE 

178  230 

9  898  347 

United  States  

84,632 

461,799 

France 

284  719 

390  254 

Italy    

70619 

151,829 

Germany 

97415 

146  470 

Austria-Hungary  

4,047 

67,623 

Spain 

6  946 

12356 

Venezuela    

10,060 

66  ECONOMIC   GEOLOGY  OF   THE  UNITED   STATES 


REFERENCES  ON  PETROLEUM 

ORIGIN,  OCCURRENCE,  AND  TECHNOLOGY.  1.  Folger,  Ann.  Kept.  Secy. 
of  Internal  Affairs,  1892,  Pt.  Ill,  p.  B.  (Petroleum  production  and 
products.)  2.  Mineral  Industry,  II :  497,  1894.  (Mining  and  Tech- 
nology.) 3.  Newberry,  Ohio  State  Agric.  Kept.,  1859.  4.  Orton, 
Geol.  Soc.  Amer.,  Bull.  IX:  85,  1892.  (Origin  and  accumulation.) 
5.  Orton,  Kentucky  Geol.  Surv.,  1894.  (Origin.)  6.  Peckham, 
Day,  Maybery,  etc.,  Proc.  Amer.  Phil.  Soc.,  XXXVI:  93.  (Origin 
and  composition.)  7.  Redwood,  B.,  Treatise  on  Petroleum.  (Ex- 
cellent.) London.  8.  White,  Geol.  Soc.  Amer.,  Bull.  Ill:  187, 
1892.  (Anticlinal  theory.)  8  a.  Oliphant,  Mineral  Census,  1902, 
Kept,  on  Mines  and  Quarries.  (General  and  statistical.) 

AREAL  REPORTS.  Alaska  :  9.  Martin,  U.  S.  Geol.  Surv.,  Bull.  225 :  365, 
1904.  Also  U.  S.  Geol.  Surv.,  Bull.  259:  129,  1905.  —  California : 
10.  Eldridge,  U.  S.  Geol.  Surv.,  Bull.  213:  306,  1903.  (General, 
good.)  11.  Mabery  and  Hudson,  Amer.  Acad.  Arts  and  Sci.,  Proc. 
XXVI:  255.  (Composition.)  12.  Watts,  Bulls.  Calif.  State  Min. 
Bureau,  No.  3  (Central  Valley),  No.  11  (Los  Angeles,  Ventura,  and 
Santa  Barbara  Cos.),  No.  19  (General.)  —  Colorado :  13.  Eldridge, 
Trans.  Amer.  Inst.  Min.  Engrs.,  XX:  442,  1892.  (Florence  field.) 
14.  Fenneman,  U.  S.  Geol.  Surv.,  Bull.  225 :  383,  1904.  (Boulder 
field.)  15.  Fenneman,  U.  S.  Geol.  Surv.,  Bull.  260:  436,  1905. 
(Florence.)  —  Indiana :  16.  Blatchley,  Ind.  Dept.  Geol.,  22d  Ann. 
Rept.:  155,  1898.  (Trenton  limestone  field.)  17.  Chapters  on 
petroleum  in  other  annual  reports  of  this  series.  18.  Ortou,  U.  S. 
Geol.  Surv.,  8th  Ann.  Rept.,  II:  475,  1889.  (Trenton  limestone.) 
—  Kansas:  19.  Adams,  U.  S.  Geol.  Surv.,  Bull.  184,  1901.  20.  Ha- 
worth,  Kansas  Geol.  Surv.,  I:  232,  1896.  (General.)  21.  See  also 
Volumes  on  Mineral  Resources,  issued  by  Kansas  Geol.  Surv.  from 
1897  to  1901.  — Kentucky:  22.  Orton,  Ky.  Geol.  Surv.,  1894.  (Gen- 
eral.)—  Louisiana:  23.  Hayes  and  Kennedy,  U.  S.  Geol.  Surv.,  Bull. 
212,  1903.  (General.)  — Michigan:  24.  Gordon,  Mich.  Geol.  Surv., 
Ann.  Rept.,  1901;  269,  1902.  (Port  Huron  field.)— New  York: 

25.  Orton,  N.  Y.  State  Mus.,  Bull.  30,   1899.     (General.)  — Ohio : 

26.  Bownocker,  Ohio  Geol.  Surv.,  4th  Series,  Bull.  1,  1903.    27.  Gris- 
wold,  U.  S.  Geol.  Surv.,  Bull.  198.     (Berea  grit  oil.)     28.  Mabery, 
Amer.  Chem.  Jour. ;  Dec.,  1895.     (Composition.)     29.  Orton,  Ohio 
Geol.  Surv.,  VI :  60.     30.  Orton,  U.  S.  Geol.  Surv.,  8th  Ann.  Rept., 
II :  475,  1889.     (Trenton  limestone  field.)  —  Pennsylvania :  31.  Carll, 
Ann.  Rept.  Pa.  Geol.  Surv.,  1885 ;  II.  1886.   32.   Reports  I  to  1 5  of 
the  same  survey.  —  Texas :  33.  Adams,  U.  S.  Geol.  Surv.,  Bull.  184, 
1901.     (General.)     34.  Hayes  and  Kennedy,  U.  S.  Geol.  Surv.,  Bull. 


PETROLEUM,   NATURAL   GAS,   OTHER   HYDROCARBONS      67 

212,  1903.  35.  Phillips,  Tex.  Univ.  Min.  Surv.,  Bull.  No.  1,  1900. 
(General.)— Washington:  36.  Landes,  Wash.  Geol.  Surv.,  I:  207. 
(General.)  — West  Virginia:  37.  White,  W.  Va.  Geol.  Surv.,  I  a  :  1, 
1904.  (General.)  38.  White,  Geol.  Soc.  Amer.,  Bull.  Ill:  187, 
1892.  (Mannington  field.) —  Wyoming:  39.  Knight  and  Slosson, 
Bull.  4,  Wyo.  School  of  Mines.  (General.)  40.  Bull.  3.  (Crook 
and  Uinta  Cos.)  41.  Bull.  5.  (Newcastle  field.)  42.  Bull.  1.  (Salt 
Creek  field.) 

REFERENCES  ON  NATURAL  GAS 

ASHBURXER.  43.  Amer.  Inst.  Min.  Engrs.,  Trans.  XIV :  428.  (Geology 
and  Distribution  in  the  United  States.)  43  a.  Orton,  Geol.  Soc.  Amer., 
Bull.  I:  87.  (Rock  pressure.)  —  California :  44.  Watts,  Calif.  Min. 
Bureau,  Bull.  3.  (Central  Valley.) — Indiana:  45.  Phinney,  U.  S. 
Geol.  Surv.,  llth  Ann.  Kept.,  I:  589,  1891.  46.  See  also  Ann. 
Repts.  Ind.  Geol.  and  Nat.  Hist.  Survey.  —  Kansas:  47.  Adams, 
U.  S.  Geol.  Surv.,  Bull.  184,  1901.  48.  Haworth,  Kan.  Geol.  Surv., 
I:  232,  1896.  (General.)  49.  Orton,  Geol.  Soc.  Amer.,  Bull.  X: 
99,  1899.  (lola  field.)  50.  Volumes  on  Mineral  Resources,  issued 
by  Kan.  Geol.  Surv.,  1897-1901.  — New  York:  51.  Orton,  N.  Y. 
State  Mus.,  Bull.  30,  1899.  (General.)  —  Ohio :  52.  Orton,  Ohio 
Geol.  Surv.,  I.  3d  ser. :  55.  53.  Orton,  U.  S.  Geol.  Surv.,  8th  Ann. 
Rept.,  II:  475,  1889.  — Pennsylvania:  54.  Carll  and  Phillips,  Ann. 
Kept.  Pa.  Geol.  Surv.,  1886,  Pt.  II,  1887.  (General.)  —  Texas : 
55.  Adams,  U.  S.  Geol.  Surv.,  Bull.  184,  1901. 

REFERENCES  ON  OIL  SHALES 

55  a.  Branner,  Amer.  Inst.  Min.  Eng.,  XXX:  537.  Brazil.)  556.  Carne, 
Memoirs,  Dept.  Mines  and  Agric.,  New  South  Wales,  Geology  No.  3. 
(General  treatise.) 

REFERENCES  ON  ASPHALTUM 

GEXERAL.  56.  Dow,  Min.  Indus.,  X:  51,  1902.  (History  of  Asphalt 
Industry.)  57.  Greene,  Amer.  Inst.  Min.  Engrs.,  Trans.  XVII :  355. 
(Uses.)  —  ORIGIN:  58.  Adams,  Amer.  lust.  Min.  Engrs.,  Trans. 
XXXIII:  340,  1903.  (Origin.)  59.  Day,  Eng.  Record,  XL:  346. 
60.  Peckham,  Amer.  Phil.  Soc.,  XXXVII:  108.  (Genesis  of 
bitumens.)  —  SPECIAL  PAPERS:  61.  Bailey  and  Ells,  Geol.  Surv.; 
Canada,  1876-77,  384.  (Albertite.)  62.  Blake,  Amer.  Inst.  Min. 
Engrs.,  Trans.  XVIII :  563.  (Uintaite,  Albertite,  and  Grahamite.) 
63.  Coleman,  Ontario  Bur.  Mines,  6th  Ann.  Rept.,  159,  1897. 
(Anthraxolite.)  —  AREAL:  64.  Cooper,  Calif.  State  Min.  Bureau, 
Bull.  16.  (California.)  65.  Crosby,  Amer.  Naturalist,  XIII:  229. 


68  ECONOMIC   GEOLOGY  OF   THE   UNITED   STATES 

(Trinidad.)  66.  Eldridge,  U.  S.  Geol.  Surv.,  22d  Ann.  Kept.,  I: 
190L  (General  occurrence  in  United  States,  excellent.)  67.  Gos- 
ling, Sch.M.  Quart.,  XVI:  41.  (Ozokerite.)  68.  Lane,  Eng.  and  Min. 
Jour.,  LXXIII:  50.  (Mich.)  69.  Merivale,  Eng.  and  Min.  Jour., 
LXVI:  790,  1898.  (Barbados.)  70.  Parker,  U.  S.  Geol.  Surv., 
19th  Ann.  Kept.,  VI  (ctd.)  :  187,  1898.  (Ozokerite.)  Also  Min. 
Ind.,  X:  50,  1902.  71.  Peckham,  Pop.  Sci.  Mo.,  LVIII:  225,  1901. 
(Trinidad  and  Venezuela.)  72.  Phillips,  Univ.  of  Tex.  Min.  Surv., 
Bull.  3,  1902.  (Texas.)  73.  Vaughn,  Eng.  and  Min.  Jour.,  LXXIII : 
344.  (Cuba.) 


CHAPTER  III 
BUILDING  STONES 

UNDER  this  term  are  included  all  stones  for  ordinary 
masonry  construction,  as  well  as  for  ornamentation,  roofing, 
and  flagging.  The  number  of  different  kinds  used  is  very 
great,  and  includes  practically  all  varieties  of  igneous,  sedi- 
mentary, and  metamorphic  rocks,  but  a  few  stand  out 
prominently  on  account  of  their  widespread  occurrence 
and  durability. 

The  cost  of  a  building  stone  naturally  exerts  decided  in- 
fluence on  its  use.  Since  the  ease  of  splitting  and  dressing 
a  stone  influences  its  cost,  the  texture  is  also  of  importance. 
Color  is  another  factor  in  determining  the  value  of  a  build- 
ing stone,  and  this,  together  with  other  considerations,  some- 
times gets  a  fashion  leading  to  the  widespread  use  of  certain 
stones.  This  has  been  well  illustrated  in  the  eastern  cities 
of  the  United  States  where,  for  many  years,  Connecticut 
browstone  was  in  such  great  demand  for  use  in  building 
private  dwellings  that  much  inferior  stone  was  put  on  the 
market.  More  recently  Indiana  limestone  and  Ohio  sand- 
stone have  met  the  popular  fancy,  and  these  two  are  now 
used  in  vast  quantities. 

Properties  of  Building  Stones  -(1-6). — The  following  prop- 
erties have  an  important  bearing  on  the  value  of  a  building 
stone :  — 


70  ECONOMIC   GEOLOGY  OF   THE  UNITED   STATES 

Color.  —  The  color  of  rocks  varies  greatly,  and  those  shown 
by  common  building  stones  include  white,  black,  brown, 
red,  yellow,  and  buff,  while  some  are  green,  blue,  or  mottled. 
The  color  may  vary  in  the  same  quarry. 

In  igneous  rocks  the  color  may  be  that  of  the  prevailing  mineral,  as 
in  pink  granite,  where  there  is  an  excess  of  pink  feldspar ;  or  it  may  be 
a  composite  due  to  the  blending  of  the  colors  of  several  minerals,  as  in 
the  case  of  ordinary  gray  granite,  where  the  color  results  from  the  mix- 
ture of  black  mica  and  whitish  quartz  and  feldspar.  Sedimentary 
rocks  commonly  owe  their  color  either  to  ferruginous  cements,  or  to 
carbonaceous  matter.  The  former  give  brown,  yellow,  red,  or  green 
colors -depending  on  the  condition  of  oxidation  of  the  iron,  while  the 
latter  produces  gray,  black,  and  bluish  tints  depending  on  the  amount 
present.  Sandstone  and  limestone  free  from  either  of  these  coloring 
agents  are  nearly  if  not  quite  white. 

Some  stones  change  color  on  exposure  to  the  air.  For  example, 
limestones  or  sandstones  containing  carbonaceous  matter  may  bleach ; 
some  black  marbles  fade  to  a  white  or  gray ;  and  many  red  and  green 
roofing  slates,  as  well  as  many  red  granites,  change  color.  Oxidation 
of  evenly  distributed  pyrite  may  change  gray  or  bluish-gray  sandstones 
to  buff  color.  If  the  minerals  responsible  for  such  change  in  color  are 
not  uniformly  distributed,  the  stone  assumes  a  blotchy  appearance,  but 
such  changes  are  not  necessarily  an  indication  of  deterioration. 

Texture.  —  Building  stones  vary  in  their  texture  from 
coarse-grained  granites  and  conglomerates  to  fine-grained 
sandstones,  limestones,  and  porphyries. 

Texture  is  an  important  property,  for  it  influences  both  the  dura- 
bility and  the  cost  of  stone.  Other  things  being  equal,  a  fine-grained 
rock  is  not  only  more  durable,  but  splits  better  and  dresses  more  evenly 
than  a  coarse-grained  rock.  Uneven  texture,  whether  due  to  mineral 
grains  or  cement,  is  undesirable  since  it  often  causes  uneven  weathering. 

Density.  —  On  the  whole,  dense  stones  resist  weather  bet- 
ter than  porous  ones,  but  there  is  great  difference  in  the 
density  of  building  stones. 


BUILDING   STONES  71 

In  general,  though  with  some  exceptions,  igneous  and  metamorphic 
rocks  have  high  density  because  of  the  close  interlocking  of  the  crystal- 
line grains.  Sedimentary  rocks  of  clastic  origin,  on  the  other  hand, 
have  less  closely  fitting  grains,  and  unless  the  latter  are  very  small,  or 
the  pores  well  filled  with  cement,  they  are  apt  to  be  porous. 

The  specific  gravity  of  a  stone  indicates  its  density ;  and  from  the 
specific  gravity  the  weight  per  cubic  foot  may  often  be  approximately 
estimated  by  multiplying  it  by  62.5,  the  weight  of  an  equal  volume  of 
water.  While  sufficiently  accurate  for  very  dense  stones  this  method  is 
liable  to  lead  to  incorrect  results  when  applied  to  very  porous  rocks. 
Following  are  some  average  specific  gravities  of  common  building 
stones,  as  given  by  Hermann  (1):  granite,  2.65;  syenite,  2.80;  serpen- 
tine, 2.60;  gneiss,  2.65;  limestone,  2.60;  dolomite,  2.80;  sandstone, 
2.10;  slate,  2.70.' 

Hardness.  —  The  hardness  of  a  building  stone  is  not  neces- 
sarily dependent  on  the  hardness  of  its  component  minerals, 
but  is  largely  influenced  by  their  state  of  aggregation. 

For  example,  a  sandstone  composed  of  quartz  grains,  but  with  little 
cementing  material,  may  be  so  soft  as  to  crumble  easily  in  the  fingers, 
while  a  limestone,  whose  grains  of  soft  carbonate  of  lime  fit  closely  and 
are  firmly  cemented,  may  be  difficult  to  break  with  a  hammer.  The 
nature  of  the  cement  in  sedimentary  rocks,  that  is  whether  it  is  lime, 
silica,  or  iron,  will  also  affect  the  hardness  of  the  stone.  Crystalline  rocks 
owe  their  great  hardness  to  the  firm  interlocking  of  the  mineral  grains. 

Strength.  —  Two  kinds  of  strength,  compressive  and  trans- 
verse, are  to  be  considered  in  building  stones. 

The  compressive  or  crushing  strength,  which  is  expressed  in  pounds 
per  square  inch,  is  the  resistance  which  the  rock  offers  to  a  crushing 
force,  and  is  dependent  chiefly  on  the  size  of  the  grains,  state  of  aggrega- 
tion, and  mineral  composition.  Because  of  the  close  interlocking  of  the 
grains  of  igneous  rocks  they  are  stronger  than  those  of  sedimentary 
origin,  in  which  the  strength  is  due  chiefly  to  the  cement  which  binds 
the  grains  together.  Sedimentary  rocks  show  greatest  strength  when 
dry,  or  when  pressure  is  applied  at  right  angles  to  the  bedding. 


72  ECONOMIC   GEOLOGY   OF  THE   UNITED   STATES 

Few  building  stones  are  subjected  to  pressures  even  approximately 
equal  to  their  crushing  strength.  No  domestic  building  stone  at  present 
used  in  the  eastern  market  has  a  crushing  strength  of  less  than  6000 
pounds,  yet  the  pressure  even  in  the  tallest  buildings  does  not  require 
a  stone  with  a  crushing  strength  exceeding  314.6  pounds,  and  this  in- 
cludes the  factor  of  safety  of  twenty  usually  allowed  by  architects. 
Computations  show  that  a  stone  at  the  base  of  the  Washington  monu- 
ment sustains  a  maximum  pressure  of  6292  pounds  per  square  inch, 
which  includes  the  usual  factor  of  safety  of  twenty ;  the  crushing  strength 
of  the  stone  used  in  the  base  of  the  monument  is  however  not  less  than 
10,000  to  12,000  pounds  per  square  inch. 

The  crushing  strength  of  some  soft  limestones  or  sandstones  may  be 
but  little  above  3000  pounds  per  square  inch,  while  that  of  diabase  often 
exceeds  30,000  pounds  per  square  inch.  The  accompanying  table  gives 
the  crushing  strength  of  a  number  of  native  stones. 

CRUSHING  STRENGTH  OF  BUILDING  STONES 

Granite,  Vinal  Haven,  Me 13,381 

Granite,  East  Saint  Cloud,  Minn.     .     .     .  28,000 

Granite,  Port  Deposit,  Md 19,750 

Dolomite  marble,  Tuckahoe,  N.Y.    .     .     .  13,076 

Limestone,  Caen,  France 3,550 

Sandstone,  Portland,  Conn 13,310 

Sandstone,  E.  Long  Meadow,  Mass.      .     .  8,812 

The  published  crushing  tests  of  different  stones  cannot  really  be  fairly 
compared  because  all  have  not  been  tested  under  exactly  the  same 
conditions. 

Transverse  Strength.  —  The  transverse  strength  is  the  load  which  a 
bar  of  stone,  supported  at  both  ends,  is  able  to  withstand  without  break- 
ing. It  is  measured  in  terms  of  the  modulus  of  rupture,  which  represents 
the  force  necessary  to  break  a  bar  of  one  square  inch  cross  section,  rest- 
ing on  supports  one  inch  apart,  the  load  being  applied  in  the  middle. 
Although  stones  in  buildings  are  rarely,  if  ever,  crushed,  they  are  fre- 
quently broken  transversely,  and  therefore  a  knowledge  of  the  transverse 
strength  is  of  more  importance  than  the  crushing  strength.  A  high 
crushing  strength  does  not  necessarily  mean  a  high  transverse  strength. 
Unfortunately  few  stones  have  been  tested  in  this  manner. 


BUILDING   STONES  73 

Porosity  and  Ratio  of  Absorption.  —  The  porosity  of  build- 
ing stones  varies  widely.  Most  igneous  rocks  have  little 
pore  space  and  hence  absorb  little  water;  but  sedimentary 
rocks,  especially  sandstones,  are  often  very  porous. 

Many  rocks,  especially  those  of  the  sedimentary  class,  contain  water 
in  their  pores  when  first  quarried.  This  is  known  to  quarrymen  as 
quarry  water,  and  it  is  present  in  some  porous  sandstones  in  sufficient 
quantities  to  interfere  with  quarrying  during  freezing  weather.  Mineral 
matter  in  solution  in  the  quarry  waters  is  deposited  between  the  grains 
when  the  water  evaporates,  often  in  sufficient  quantities  to  perceptibly 
harden  the  stone. 

Water  is  also  present  in  the  joint  planes,  and  by  its  passage  along 
these  planes  causes  oxidation  and  rusting  of  the  iron  of  the  rock-forming 
minerals.  This  discolors  the  stone  along  and  on  either  side  of  the  joint 
planes,  giving  rise  to  a  yellow  color  known  as  sap. 

Resistance  to  Frost.  —  Building  stones  show  a  varying 
degree  of  resistance  to  frost. 

Dense  rocks,  like  granites,  quartzites,  and  many  limestones,  and  even 
some  very  porous  rocks,  are  little  affected ;  but  many  porous  and  lami- 
nated rocks,  like  open  sandstones  and  schists,  disintegrate  under  frost 
action.  This  is  due  to  the  fact  that  moisture  absorbed  in  the  warmer 
weather,  on  freezing  in  the  pores,  expands,  and  either  forces  off  small 
pieces  or  disrupts  the  stones.  Since  clay  readily  absorbs  water,  clayey 
rocks  are  sometimes  similarly  affected. 

Resistance  to  Heat.  —  All  rocks  expand  when  heated,  and 
contract  when  cooled,  but  do  not  shrink  down  to  their 
original  dimensions.  This  permanent  increase  in  size  is 
termed  permanent  swelling,  and  though  small  when  figured 
for  one  linear  foot,  is  appreciable  in  long  pieces. 

The  following  figures  give  the  average  of  a  number  of  tests  of  per- 
manent swelling  in  stone  bars  20  inches  long,  heated  from  32°  F.  to 
212°  F.,  and  then  cooled  to  the  original  temperature:  granite,  .009 


74  ECONOMIC   GEOLOGY   OF   THE   UNITED   STATES 

inches;  marble,  .009  inches;  limestone  and  dolomites,  .007  inches; 
sandstone,  .0047  inches. 

The  most  severe  test  of  a  stone's  resistance  to  rapid  changes  of 
temperature  is  to  heat  it  to  about  800°  C.  and  then  immerse  it  in  cold 
water.  Quartzites  and  hard  sandstones  withstand  such  treatment  best ; 
some  granites  crack  and  crumble,  and  the  carbonate  rocks  change  to 
lime. 

Structural  Features  affecting  Quarrying.  —  All  rocks  are  traversed  by 
planes  of  separation  of  one  sort  or  another.  In  sedimentary  rocks  these 
consist  of  bedding  and  joint  planes ;  in  igneous  rocks,  the  latter  alone 
are  present;  and  in  metamorphic  rocks,  joint  planes,  a  banding  of 
minerals,  and,  very  often,  cleavage  planes. 

Bedding  Planes.  —  These  may  be  either  an  advantage  or  a  disadvan- 
tage to  the  quarryman.  They  are  desirable  because  they  facilitate  the 
extraction  of  the  stone ;  but  if  numerous  and  closely  spaced,  the  layers 
may  be  too  thin  for  any  purpose  except  nagging.  They  often  serve 
as  a  means  of  entrance  for  the  agents  of  weathering,  and  the  stone 
may  be  disintegrated  along  the  bedding  planes  while  elsewhere  fresh. 

Incipient  planes  of  weakness,  due  either  to  the  arrangement  of 
minerals  or  to  microscopic  fractures  in  them,  often  give  rise  to  planes 
of  easy  splitting  which  are  of  great  value  in  quarrying,  notably  of 
granite.  Such  planes  which  permit  splitting  in  approximately  horizon- 
tal directions  are  called  lift ;  the  most  prominent  vertical  plane  is  called 
rift ;  and  a  less  prominent  vertical  plane,  approximately  at  right  angles 
to  the  rift,  is  called  the  cut  off. 

The  position  of  the  beds  exerts  an  important  influence  on  the  cost 
of  quarrying.  When  horizontal  and  of  different  quality,  it  may  often 
be  necessary  to  strip  off  worthless  rock  in  order  to  reach  the  beds  of 
good  quality.  In  such  cases,  there  is  often  less  stripping  to  do  in 
quarries  opened  on  gently  sloping  ground.  In  regions  of  steep  dip,  it 
is  sometimes  possible  to  work  the  quarry  as  a  cut,  extracting  the  desired 
beds  and  leaving  useless  ones  standing. 


BUILDING   STONES  75 


GRANITES 

Characteristics  of  Granites  (3). — As  commonly  used  by 
quarrymen,  the  term  granite  includes  all  igneous  rocks 
and  gneiss  ;  but  in  this  book  it  is  used  in  the  geological 
sense,  which  is  more  restricted.  From  the  geological  stand- 
point a  granite  is  a  holocrystalline,  plutonic  igneous  rock 
consisting  of  quartz,  orthoclase  feldspar,  and  either  mica 
or  hornblende,  or  both.  There  are  also  varying  but  usually 
small  quantities  of  other  feldspars,  and  there  may  be  sub- 
ordinate accessory  minerals,  such  as  pyrite,  garnet,  tourma- 
line, and  epidote. 

Granites  vary  in  texture  from  fine  to  coarse  grained,  and 
in  some  cases  are  porphyritic.  They  pass  into  gneisses  by 
such  insensible  gradations  that  no  sharp  line  can  be  drawn 
between  the  two.  In  color  they  vary,  being,  most  com- 
monly, gray,  mottled  gray,  red,  pink,  white,  or  green, 
according  to  the  color  or  abundance  of  the  component 
minerals.  Most  granites  are  permanent  in  their  color,  but 
some  of  bright  red  color  bleach  on  exposure  to  weather. 

The  average  specific  gravity  of  granites  is  2.66,  which  corresponds 
to  a  weight  of  166.5  pounds  per  cubic  foot.  They  commonly  contain 
less  than  1  per  cent  of  water,  and  often  absorb  two  or  three  tenths 
more.  Their  crushing  strength  varies,  but  is  apt  to  lie  between  15,000 
and  30,000  pounds  per  square  inch. 

Granites  are  among  the  most  durable  of  building  stones,  but  there 
is  some  variation  in  the  durability  of  the  different  kinds.  Other  things 
being  equal,  fine-grained  granites  are  more  durable  than  coarse-grained, 
being  less  easily  affected  by  changes  of  temperature.  One  of  the 
most  beautiful  granites  known,  the  Rapikivi  granite  of  Finland,  lacks 
in  durability  on  this  account.  Pyrite  and  marcasite  are  injurious 
minerals,  since  they  rust  rapidly  and  may  discolor  the  stone  in  an 


76 


ECONOMIC    GEOLOGY   OF   THE   UNITED   STATES 


unsightly  manner.  Very  few  granites  now  in  use  show  signs  of  decay; 
but  in  those  that  do,  the  darker  silicates  are  rusted,  the  luster  of  the 
feldspar  is  dulled,  and,  in  some  cases,  the  stone  has  begun  to  disinte- 
grate. Some  red  granites  bleach  on  continued  exposure  to  sunlight. 

Distribution  of  Granites  in  the  United  States  (3).  — Granite 
usually  occurs  in  great  bosses  frequently  forming  the  cores 
of  mountain  chains.  Removal  of  the  overlying  strata  by 


FIG.  20.  —  Map  showing  distribution  of  crystalline  rocks  (mainly  granites)  in 
United  States.    After  Merrill.     Stone  for  Building  and  Decoration. 

denudation  has  revealed  the  granite,  which,  owing  to  its 
greater  durability,  is  often  left  standing  as  peaks  or  domes 
by  the  farther  removal  of  the  surrounding,  weaker  strata. 
Granites  show  a  wide,  geologic  range,  but  most  known 
occurrences  are  associated  with  the  older  formations. 

Granite  forms  an  important  source  of  durable  building 
stone  widely  distributed  in  the  United  States  (Fig.  20)  ; 
but  nearly  70  per  cent  of  that  quarried  comes  from  the 


BUILDING   STONES  77 

Atlantic  states.  There  are  several  areas  which  will  be 
briefly  considered. 

Eastern  Crystalline  Belt  (3,  8,  15,  21,  25,  32,  33).  —  From 
northeastern  Maine  south  west  ward  to  eastern  Alabama 
there  is  an  important  belt  of  granites  and  gneisses,  mostly 
of  pre-cambrian  age.  Those  at  the  northeastern  end  of 
the  belt,  as  far  south  as  New  York,  are  most  extensively 
quarried,  largely  because  of  their  peculiarly  favorable  loca- 
tion. In  this  belt  those  of  Quincy,  Massachusetts,  Barre, 
Vermont,  and  Westerly,  Rhode  Island,  are  of  value  for 
monumental  work. 

Central  States.  —  In  these  states  there  are  several  widely 
separated  areas  :  (1)  the  Minnesota- Wisconsin  area  (35), 
affording  many  fine  stones ;  (2)  the  southeastern  Missouri 
area ;  (3)  east  central  Arkansas ;  and  (4)  Llano  County, 
Texas,  all  supplying  stones  of  excellent  quality. 

Western  States.  —  There  are  many  granite  areas  in  the 
Cordilleras,  including  stone  of  various  colors  and  texture; 
but  quarrying  is  almost  entirely  confined  to  California  (12), 
Colorado  (13),  Montana,  Washington  (34),  and  Oregon  for 
local  use.  The  supply  is  inexhaustible.  There  is  some 
quarrying,  also,  in  the  enormous  mass  of  coarse-grained 
granite  which  forms  the  central  portion  of  the  Black  Hills 
of  South  Dakota. 

Uses  of  Granite.  —  On  account  of  its  massive  character 
and  durability,  granite  is  much  employed  for  massive 
masonry  construction,  while  some  of  the  granites  that  take 
and  preserve  a  high  polish,  and  are  susceptible  of  being 
carved,  are  in  great  demand  for  ornamental  and  monumen- 
tal work.  Because  of  its  greater  durability,  granite  has 


78  ECONOMIC   GEOLOGY   OF   THE   UNITED   STATES 

in   recent   years   largely   replaced   marble  for   monumental 
purposes. 

The  refuse  of  the  quarries  is  often  dressed  for  paving 
blocks  or  crushed  for  roads  and  railroad  ballast.  The  size 
of  the  blocks  which  can  be  extracted  from  a  granite  quarry 
depends  in  part  on  the  spacing  of  the  joint  planes,  in  part 
on  the  perfection  of  development  of  the  rift,  some  of  the 
monoliths  that  have  been  quarried  being  of  immense  size  ; 
for  example,  one  from  Stony  Creek,  Connecticut,  measured 
41  ft.  x  6  ft.  x  6  ft. ;  one  from  Vinal  Haven,  Maine,  60  ft. 
X  5£  ft. ;  one  from  Barre,  Vermont,  60  ft.  x  7  ft.  x  6  ft. 

Miscellaneous  Igneous  Rocks.  —  Other  igneous  rocks  than  granites 
are  little  used  for  structural  work,  though  they  are  quarried  in  some 
localities.  For  example,  the  diabase,  or  trap,  so  abundant  in  the  Tri- 
assic  of  the  eastern  states,  is  occasionally  used  for  dimension  blocks, 
but  its  chief  value  is  for  paving  blocks  and  road  metal.  The  basaltic 
rocks  of  the  western  states  are  often  employed  for  similar  purposes. 
Norites  of  great  beauty  occur  in  New  York,  and  syenites  of  excellent 
quality  have  been  quarried  in  Arkansas.  Diorites  are  also  quarried  at 
scattered  localities.  Some  of  the  porphyries  and  rhyolites  of  the  Atlan- 
tic States  possess  considerable  beauty  when  polished.  A  handsome 
porphyry  is  quarried  in  Wisconsin  (35),  and  in  the  Cordilleran  region 
both  rhyolite  and  porphyry  occur  in  numerous  localities.  A  pink  rhyo- 
lite  and  consolidated  volcanic  tuffs  are  used,  to  some  extent,  for 
building  in  Arizona. 

LIMESTONES  AND  MARBLES 

General  Characteristics  (1.3). — A  great  series  of  sedi- 
mentary and  metamorphic  rocks,  composed  chiefly  of  car- 
bonate of  lime,  or,  in  the  case  of  dolomite,  of  carbonate  of 
lime  and  magnesia,  is  included  under  the  term  limestone 
and  marble.  These  rocks  also  contain  varying,  but  usually 
small  amounts  of  iron  oxide,  iron  carbonate,  silica,  clay, 


BUILDING    STONES  79 

and  carbonaceous  matter.  When  of  metamorphic  character, 
various  silicates,  such  as  mica,  hornblende,  and  pyroxene, 
may  be  present. 

These  calcareous  rocks  vary  in  texture  from  fine-grained, 
earthy,  to  coarse-textured,  fossiliferous  rocks,  and  from 
finely  crystalline  to  coarsely  crystalline  varieties.  There 
is,  also,  great  range  in  color,  the  most  common  being  blue, 
gray,  white,  and  black,  but  beautiful  shades  of  yellow,  red, 
pink,  and  green,  usually  due  to  iron  oxides,  are  also  found. 
Their  crushing  strength  commonly  ranges  from  10,000 
to  15,000  pounds  per  square  inch,  while  their  absorption  is 
generally  low. 

The  mineral  composition  of  limestone  exerts  a  strong 
influence  on  its  durability.  Those  limestones  which  are 
composed  chiefly  or  wholly  of  carbonate  of  lime  are  liable 
to  solution  in  waters  containing  carbon  dioxide ;  but  dolo- 
mite limestones,  especially  coarse-grained  ones,  disintegrate 
rather  than  decompose.  Streaks  of  mineral  impurities  cause 
the  stone  to  weather  unevenly.  Pyrite  is  an  especially  inju- 
rious constituent,  not  only  on  account  of  its  rusting,  but 
also  because  the  sulphuric  acid  set  free  by  its  decompo- 
sition attacks  the  stone.  Black  or  gray  limestones  will 
sometimes  bleach  on  exposure. 

Varieties  of  Limestones.  —  In  the  geological  sense  limestones  are  of 
sedimentary  origin,  while  marbles  are  of  metamorphic  character,  but 
in  the  trade  the  term  marble  is  applied  to  any  calcareous  rock  capable 
of  taking  a  polish.  In  addition  to  the  different  varieties  of  marble 
and  the  ordinary  limestones  there  are  certain  kinds  of  calcareous  rock 
to  which  special  names  are  given,  as  follows :  — 

Dolomite,  or  dolomitic  limestone,  composed  of  carbonate  of  lime  and 
magnesia,  and  to  the  eye  alone  often  is  indistinguishable  from  lime- 
stone. 


80  ECONOMIC    GEOLOGY   OP   THE   UNITED   STATES 

Oolitic  limestone,  composed  of  small,  rounded  grains  of  concretionary 
character. 

Travertine,  or  calcareous  tufa,  a  limestone  deposited  from  springs. 
It  is  often  sufficiently  hard  and  durable  for  building,  but  rarely  occurs 
in  deposits  of  large  size. 

Stalactitic  and  stalagmitic  deposits,  formed  on  the  roofs  and  floors  of 
caves,  respectively,  are  often  of  crystalline  texture  and  beautifully 
colored,  and,  when  of  sufficient  solidity,  are  known  as  onyx  marble. 

Fossiliferous  limestones  is  a  general  term  applied  to  those  limestones 
which  contain  many  fossil  remains.  Under  this  heading  are  included 
crinoidal  limestone  and  coral-shell  marble.  Coquina  is  a  loosely 
cemented  shell  aggregate,  like  that  found  near  St.  Augustine,  Florida. 
Chalk  is  a  fine,  white,  earthy  limestone,  composed  chiefly  of  forami- 
niferal  remains. 

Distribution  of  Limestones  in  the  United  States.  —  Lime- 
stones are  found  in  many  states,  and  in  all  geological  for- 
mations from  Cambrian  to  Tertiary,  but  those  of  the 
Paleozoic,  which  are  much  used  in  the  Eastern  and  Central 
states,  are  more  extensive  and  more  massive  than  those  of 
later  formations.  Although  many  large  quarries  have  been 
opened  to  supply  a  local  demand,  the  product  is  shipped 
to  a  distance  from  only  a  few  localities.  At  present  the 
sub-Carboniferous  Bedford  O8)  oolitic  limestone  of  Indiana 
(PI.  VI)  is,  perhaps,  the  most  widely  used  limestone  in  the 
United  States.  It  occurs  in  massive  beds  from  20  to  70 
feet  thick,  and  is  said  to  underlie  an  area  of  more  than 
70  square  miles.  Although  soft  and  easily  dressed,  it  has 
good  strength,  and  has  been  used  in  many  important  cities 
of  the  United  States. 

Cretaceous  limestones  are  worked  in  Kansas,  Nebraska, 
and  Iowa,  although  the  most  important  sources  are  in  the 
Paleozoic  formations. 


PLATE  VI 


BUILDING   STONES 


81 


Distribution  of  Marbles  in  the  United  States  (3).  —While 
some  variegated  marble  is  produced  in  the  United  States, 


FIG.  21.  —  Map  showing  marble  areas  of  eastern  United  States.    After  Merrill. 
Stones  for  Building  and  Decoration. 

still  most  of  those  quarried  are  white,  the  greater  part  of 
the  variegated  stones  being   imported.     The  main  supply 


82  ECONOMIC    GEOLOGY   OF   THE   UNITED   STATES 

comes  chiefly  from  regions  of  metamorplaic  rock,  the  eastern 
crystalline  belt  being  the  principal  producer  (Fig.  21). 
Vermont  (32,  33)  leads  all  other  states  in  marble  produc- 
tion, supplying  80  per  cent  of  all  the  marble  used  for 
ornamental  work  in  the  country.  The  most  important 
and  largest  quarries  are  those  at  Proctor  (PL  VII)  and 
West  Rutland,  where  a  thick  and  steeply  dipping  bed  of 
marble  occurs  between  other  limestones.  The  marble  bed, 
which  has  a  thickness  of  150  feet  at  the  top  of  the  quarry, 
narrowing  to  75  feet  at  the  bottom,  is  divisible  into  a 
series  of  well-marked  layers  of  varying  thickness,  quality, 
and  color,  —  white,  blue,  gray,  and  striped  (33).  Similar 
marbles  are  quarried  in  Massachusetts  (3,  22),  New  York 
(3,  28),  Maryland  (21),  and  Georgia  (15). 

A  variegated  red  and  white  marble  of  some  hardness  is 
quarried  at  S wanton,  Vermont  (33),  the  brilliant  red  being 
caused  by  iron  oxide,  the  white  by  calcite  deposited  in 
breccia  cavities. 

The  Trenton  limestone  in  eastern  Tennessee  (3)  supplies 
marbles  of  pinkish  chocolate  color  with  white  variegation ; 
and  certain  layers  are  rendered  peculiarly  beautiful  by  the 
replacement  of  the  fossils  by  calcite.  It  is  used  chiefly  for 
interior  decoration. 

Marble  has  been  reported  from  various  states  west  of  the 
Mississippi,  but  as  yet  little  quarrying  has  been  done.  That 
quarried  in  Inyo  County,  California,  has  attracted  con- 
siderable attention  in  recent  years. 

Most  of  the  variegated  marble  used  for  interior  decoration  in  this 
country  is  obtained  from  abroad,  although  ornamental  stones  of  this 
class  occur  in  the  United  States;  however,  up  to  the  present  time  few 
attempts  have  been  made  to  place  them  on  the  market.  This  may  be 


PLATE  VII 


Marble  quarry,  Proctor,  Vt.  Photo.,  Vermont  Marble  Co.  The  banding  of  the  rock 
is  vertical.  The  horizontal  lines  are  caused  by  the  stone  being  quarried  in 
benches. 


BUILDING  STONES  83 

due  to  the  fact  that  few  quarrymen  care  to  assume  the  temporary  expense 
which  their  introduction  might  involve. 

Onyx  Marbles  (37-40).  —  Under  this  term  are  included  two  types  of 
calcareous  rock,  one  a  hot-spring  deposit,  or  travertine,  formed  at  the 
surface,  the  other  a  cold-water  deposit  formed  in  limestone  caves  in 
the  same  manner  as  stalagmites  and  stalactites.  Cave  onyx  is  more 
coarsely  crystalline  and  less  transluscent  than  travertine  onyx.  The 
beautiful  banding  of  onyx  is  due  to  the  deposition  of  successive  layers 
of  carbonate  of  lime,  while  the  colored  cloudings  and  veinings  are 
caused  by  the  presence  of  metallic  oxides,  especially  iron. 

Neither  variety  of  onyx  occurs  in  extensive  beds,  though  both  are 
widely  distributed.  Onyx  is  found  in  Arizona,  California,  and  Colorado, 
but  it  has  not  been  developed  in  any  of  these  states  except  on  a  small 
scale.  Most  of  the  onyx  used  in  the  United  States  is  obtained  from 
Mexico,  though  small  quantities  are  obtained  from  Egypt  and  north 
Algeria. 

The  value  of  onyx  varies  considerably,  the  poorer  grades  selling  for 
as  little  as  50  cents  per  cubic  foot,  while  the  higher  grades  bring  $50 
or  more.  The  earliest-worked  deposits  were  probably  those  of  Egypt, 
which  were  used  by  the  ancients  for  the  manufacture  of  ornamental 
articles  and  religious  vessels;  and  the  Romans  obtained  onyx  from  the 
quarries  of  northern  Algeria.  Many  of  the  travertine  onyx  deposits 
occur  in  regions  of  recent  volcanic  activity,  and  all  of  the  known 
occurrences  are  of  recent  geological  age. 

SERPENTINE 

Pure  serpentine  is  a  hydrous  silicate  of  magnesia;  but  beds  of  ser- 
pentine are  rarely  pure,  usually  containing  varying  quantities  of  such 
impurities,  as  iron  oxides,  pyrite,  hornblende,  and  carbonates  of  lime 
and  magnesia.  The  purer  varieties  are  green  or  greenish  yellow,  while 
the  impure  types  are  various  shades  of  black,  red,  or  brown.  Spotted 
green  and  white  varieties  are  called  ophiolite  or  ophicalite. 

Serpentine  is  sometimes  found  in  sufficiently  massive  form  for  use  in 
structural  or  decorative  work;  but,  owing  to  the  frequent  and  irregu- 
lar joints  found  in  nearly  all  serpentine  quarries,  it  is  difficult  to  obtain 
other  than  small-sized  slabs.  Its  softness  and  beautiful  color  have  led 


81  ECONOMIC   GEOLOGY   OF   THE   UNITED   STATES 

to  its  extensive  use  for  interior  decoration ;  but  since  it  weathers  irregu- 
larly and  loses  luster,  it  is  not  adapted  to  exterior  work. 

Though  found  in  a  number  of  states,  most  of  the  numerous  attempts 
to  quarry  American  serpentine  have  been  unsuccessful.  Considerable 
serpentine  for  ordinary  structural  work  has  been  quarried  in  Chester 
County,  Pennsylvania,  and  a  variety  known  as  Verdolite  is  worked 
near  Easton,  Pennsylvania.  Quarrying  operations  are  also  under  way 
in  the  state  of  Washington. 

SANDSTONES 

General  Properties  (1,  3). — While  most  sandstones  are 
composed  chiefly  of  quartz  grains,  some  varieties  contain 
an  abundance  of  other  minerals,  such  as  mica,  or,  more 
rarely,  feldspar,  which  in  rare  cases  may  even  form  the 
predominating  mineral.  Pyrite  is  occasionally  present,  and 
varying  amounts  of  clay  frequently  occur  between  the 
grains,  at  times  in  sufficient  quantity  to  materially  influence 
the  hardness  and  dressing  qualities  of  the  stone.  The  hard- 
ness of  sandstones,  however,  usually  depends  on  the  amount 
and  character  of  the  cement,  varying  from  those  having 
so  small  an  amount  of  silica  or  iron  oxide  cement  that 
the  stone  crumbles  in  the  fingers  to  those  quartzites  whose 
grains  are  so  firmly  bound  by  silica  that  the  rock  resembles 
solid  quartz.  With  these  differences  the  chemical  compo- 
sition varies  from  nearly  pure  silica  to  sandstone  with  a 
large  percentage  of  other  compounds.  (For  analyses,  see 
Kemp's  "Handbook  of  Rocks.") 

There  are  many  colors  among  sandstones,  but  light  gray, 
white,  brown,  buff,  bluish  gray,  red,  and  yellow  are  most  com- 
mon. In  density  sandstones  range  from  the  nearly  imper- 
vious quartzites  to  the  porous  sandrocks  of  recent  geologic 
formations,  and  consequently  they  show  a  variable  absorption. 


BUILDING   STONES  85 

Most  sandstones  contain  some  quarry  water,  and  those  with 
appreciable  amounts  are  softer  and  more  easy  to  dress  when 
first  quarried ;  but  they  cannot  be  quarried  in  freezing 
weather.  The  average  specific  gravity  of  sandstone  is  2.3, 
and  accordingly  a  cubic  foot  weighs  about  140  to  150  pounds. 
On  the  whole,  sandstones  resist  heat  well  and  are  usually 
of  excellent  durability,  since  they  contain  few  minerals  that 
easily  decompose.  When  they  disintegrate  it  is  commonly 
by  frost  action.  The  injurious  minerals  are  pyrite,  mica, 
and  clay.  Pyrite  is  likely  to  cause  discoloration  on  weather- 
ing ;  the  presence  of  mica  tends  to  cause  the  stone  to  scale 
off  if  set  on  edge ;  and  clay  may  cause  injury  to  the  stone  in 
freezing  weather  on  account  of  its  capacity  for  absorbing 
moisture.  The  value  of  a  sandstone  is  often  lessened  by 
careless  quarrying,  or  by  placing  it  on  edge  in  the  building, 
thus  exposing  the  bedding  planes  to  the  entrance  of  water. 

Varieties  of  Sandstone.  —  With  an  increase  in  the  size  of 
their  grains,  sandstones  pass  into  conglomerates  on  the  one 
hand  and  with  an  increase  in  clay  into  shales.  By  an  in- 
crease in  the  percentage  of  carbonate  of  lime  they  may  also 
grade  into  limestones. 

On  account  of  these  variations,  as  well  as  the  difference  in  color  and 
the  character  of  the  cement,  a  number  of  varieties  of  sandstone  are 
recognized,  of  which  the  following  are  of  economic  value:  arkose,  a 
sandstone  composed  chiefly  of  feldspar  grains ;  flagstone,  a  thinly  bedded, 
argillaceous  sandstone  used  chiefly  for  paving  purposes  ;  bluestone,  a  flag- 
stone much  quarried  in  New  York ;  freestone,  a  sandstone  which  splits 
freely  and  dresses  easily;  brownstone,  a  term  formerly  applied  to  sand- 
stones of  brown  color,  obtained  from  the  eastern  Triassic  belt,  and  since 
stones  of  other  colors  are  now  found  in  the  same  formation,  the  term 
has  come  to  have  a  geographic  meaning  and  no  longer  refers  to  any 
specific  physical  character. 


86  ECONOMIC   GEOLOGY   OF   THE   UNITED   STATES 

Distribution  of  Sandstones  in  the  United  States.  —  Sand- 
stones occur  in  all  formations  from  pre-Cambrian  to  Ter- 
tiary. They  are  so  widely  distributed  that  for  local  supply 
there  are  numerous  small  quarries  in  many  states,  but  there 
are  several  areas  which  have  been  operated  on  an  extensive 
scale,  some  of  them  for  many  years.  Of  these,  one  of  the 
best  known  is  the  Triassic  Brownstone  belt,  which  extends 
from  the  Connecticut  Valley  in  Massachusetts  southwest- 
ward  into  North  Carolina. 

Among  the  Paleozoic  strata  there  are  many  sandstones, 
often  massive,  and  usually  dense  and  hard.  Of  these  the 
Medina  and  Potsdam  are  specially  important  and  much 
quarried  in  New  York  State  (27,  28).  The  same  forma- 
tions extend  southward  along  the  Appalachians  and  are 
available  at  several  points.  Devonian  flagstones  are  ex- 
tensively quarried  at  several  localities  in  New  York  and 
Pennsylvania.  At  the  present  time  the  Lower  Carbon- 
iferous Berea  sandstone  of  Ohio  (29)  is  in  great  demand 
because  of  its  light  color,  even  texture,  and  the  ease  with 
which  it  is  worked.  Moreover,  it  has  the  peculiar  property 
of  changing  to  a  uniform  buff  on  exposure  to  the  air.  There 
are  numerous  other  Paleozoic  sandstones  in  the  central 
states,  among  them  the  Potsdam  which  covers  a  wide  area 
in  Michigan  and  Wisconsin  (35).  Some  of  this  stone  is 
bright  red  in  color. 

The  Mesozoic  and  Tertiary  strata  of  the  West  contain  an 
abundance  of  sandstone  strata,  and  quarries  opened  in  many 
of  them  yield  a  good  quality  of  stone.  Though  usually  less 
dense  and  hard  than  the  Paleozoic  sandstones,  they  serve 
admirably  for  buildings  in  the  mild  or  dry  climates  of  the 
West. 


BUILDING   STONES 


87 


Uses  of  Sandstones.  —  The  wide  distribution  of  sandstones 
makes  them  an  important  source  of  local  structural  material. 
They  are  chiefly  used  for  ordinary  building  work,  and  but 
little  for  massive  masonry  or  monuments.  The  thin-bedded 
flagstones  are  much  used  for  flagging,  and  some  of  the 
harder  sandstones  are  split  up  for  paving  blocks.  For  other 
uses,  see  Abrasives. 

SLATES 

General  Characteristics  (3,  26). — Slates  are  metamorphic 
rocks  derived  from  clay  or  shale  or  more  rarely  from  igneous 
rocks  (11).  Their  value  depends  upon  the  presence  of  a 
well-defined  plane  of  splitting,  called  cleavage  (Fig.  22),  de- 
veloped by  metamorphism  through  the  rearrangement  and 
flattening  of  the  original 
mineral  grains  and  the  E 
development  of  mica- 
ceous minerals.  The 
cleavage  usually  de- 
velops at  a  variable 
angle  to  the  bedding 
planes  which  are  often 
completely  obliterated  by  the  metamorphism.  When  not 
completely  destroyed  the  bedding  planes  are  marked  by 
parallel  bands,  called  ribbons,  cutting  across  the  planes  of 
cleavage,  but  so  perfect  is  the  cleavage  in  the  best  slates  that 
the  rock  readily  splits  into  thin  sheets  with  a  smooth  surface. 

Slates  are  commonly  so  fine  grained  that  the  mineral  com- 
position is  not  evident  to  the  eye,  but  the  microscope  re- 
veals the  presence  of  many  of  the  varied  mineral  grains 
found  in  shale,  and  in  addition  much  chlorite,  developed  by 


QUARRY  FLOOR 


FIG.  22.  —  Section  showing  cleavage  and  bed- 
ding in  slate.  After  Dale,  U.  S.  Geol.  Surv., 
19th  Ann.  Kept.,  III. 


88  ECONOMIC    GEOLOGY   OF   THE    UNITED    STATES 

metamorphism.  Owing  to  the  presence  of  carbonaceous 
particles,  most  slates  are  black  or  bluish  black,  but  green, 
purple,  and  red  slates  are  also 
known.  The  specific  gravity  of 
slate  is  about  2.7,  and  a  cubic 
foot  weighs  between  170  and  175 
pounds. 

Most  slates  are  fairly  durable, 
,.     ~^  7  though    the    presence    of    pyrite 


FIG.  23.  — Section  in  slate  quarry 

with  cleavage  parallel  to  bed-  their  decay.     Some  colored  slates 

ding,     a,  purple  slate;  6,  un- 

worked;  c  and  d,  variegated ;   fade  on  exposure  to  the  weather, 

e  and  f,  green;  g  and  h,  gray    ,      ,     ,,  .        ,  ,  .   ,     .       , 

green ;»,  quartette  tf.gray with    but   this   change,   which   IS   due   to 
black  patches.    After  Dale.        ^   bleaching    of    certain   mineral 

grains,  does  not  necessarily  result  in  loss  of  strength  or 
disintegration. 

Distribution  of  Slates  in  the  United  States.  —  Since  slates 
are  of  metamorphic  origin,  they  are  limited  to  those  regions 
in  which  the  rocks  are  metamorphosed,  and  at  present  the 
greater  part  of  our  supply  comes  from  the  Cambrian  and 
Silurian  strata  of  the  eastern  crystalline  belt  of  the  Atlantic 
states. 

A  series  of  quarries  producing  red,  green,  purple,  and 
variegated  slates  are  located  in  a  belt  of  Cambrian  and 
Hudson  River  strata  along  the  border  of  New  York  (PL 
VIII)  and  Vermont  (26,33). 

Black  slates  are  quarried  in  Maine  (3),  New  Jersey  (3), 
Pennsylvania  (3),  Maryland  (21),  Georgia  (3),  and  Virginia 
(3).  Other  producing  states  are  Minnesota,  California  (11), 
and  Arkansas  (9). 


ROBERT  W.  WEBB 
GEOLOGY  DEPT.,  U.C.LA 


PLATE  VIII 


View  of  green-slate  quarry,  Pawlet,  Vt.    Photo,  by  H.  Ries. 


BUILDING   STONES 


89 


Uses  of  Slate.  —  Slate  is  best  known  as  a  roofing  material, 
but  it  is  also  used  for  mantels,  billiard-table  tops,  floor  tiles, 
steps,  flagging,  slate  pencils,  acid  towers,  wash  tubs,  etc. 
The  process  of  marbleizing  slates  for  mantels  and  fireplaces 
is  carried  on  at  several  localities. 

In  quarrying  slate  there  is  from  40  to  60  per  cent  waste, 
which  is  greater  than  in  any  other  building  stone;  but  the 
introduction  of  channeling  machines  in  quarrying  has  done 
much  to  reduce  this.  The  discovery  of  a  use  for  this  waste 
has  been  an  important  problem,  which  has  thus  far  been  only 
partially  solved.  It  is  sometimes  ground  for  paint,  and 
attempts  have  been  made  to  utilize  it  in  the  manufacture 
of  bricks  and  Portland  cement. 

Production  of  Building  Stones. — The  production  of  build- 
ing stones  by  kinds  for  several  years  was  as  follows:  — 


PRODUCTION  OF  BUILDING  STONES  IN  THE 
UNITED  STATES 

1900 

1901 

1902 

1903 

Granite  and  Trap  . 
Marble      .... 
Slate    

$12,675,617 
4,267,253 
4,240,466 

6,471,384 
16,666,62s1 

$15,976,961 
4,965,699 
4,787,525 

8,138,680 
21,747,061! 

$18,257,944 
5,044,182 
5,696,051 

10,601,171 

24,959,751  1 

$18,436,087 
5,362,686 
6,256,885 

11,262,259 
26,642,551  * 

Sandstone  and 
Bluestone  .     .     . 
Limestone     .     .     . 

Total     .... 

44,321,345 

55,615,926 

64,559,099 

67,960,468 

The  value  of  the  building  stones  produced  by  the  several 
more  important  states,  together  with  the  kind  of  stone  pro- 
duced chiefly  in  1903,  is  given  below. 


i  Does  not  include  limestone  used  as  flux. 


90 


ECONOMIC  GEOLOGY  OF  THE  UNITED  STATES 


PRODUCTION  OF  BUILDING  STONES  IN  MORE 

IMPORTANT  STATES  IN  1903 

TOTAL  VALUE 

KIND  PRODUCED  CHIEFLY 

Pennsylvania     .    . 

$12,589,202 

Limestone 

Vermont  .... 

5,889,208 

Marble 

3  611  140 

Granite 

Ohio     .    .         .     . 

5,280,472 

Limestone 

New  York     .     .    . 

5,182.850 

Limestone 

Massachusetts   .     . 

4,443,601 

Granite 

Indiana     .... 

2,903,284 

Limestone 

Georgia    .... 

1,577,134 

Granite 

Maryland      .     .     . 

1,344,722 

Granite 

All  others      .    .     . 

42,821,613 

In  1903  the  slate  exported  was  valued  at  $628,612. 

REFERENCES  ON  BUILDING  STONES 

GENERAL  ON  PROPERTIES.  1.  Hermann,  Steinbruchindustrie  und  Stein- 
bruchgeologie,  Berlin,  1899.  Borntrager  Bros.  2.  Merrill,  Min- 
eral Census,  1902.  (Mines  and  Quarries.)  3.  Merrill,  Stones  for 
Building  and  Decoration,  3d  ed.,  New  York,  1904.  Wiley  &  Sons. 
For  general  information  on  properties  and  testing  see  also,  4.  Buck- 
ley, Jour.  Geol.,  VIII:  160  and  333,  1900.  5.  Julien,  Jour. 
Frankl.  Inst.,  CXLVII,  1899.  6.  MerriU,  Maryland  Geol.  Surv.,  II  : 
47,  1898.  7.  Watson,  Ga.  Geol.  Surv.,  Bull.  9-A,  1903. 

AREAL  REPORTS.  Alabama :  8.  Smith,  Eng.  and  Min.  Jour.,  LXVI :  398. 
(General.)— Arkansas:  9.  Dale,  U.  S.  Geol.  Surv.,  Bull.  225:  414, 
1904.  (Slate.)  10.  Hopkins,  Ark.  Geol.  Surv.,  Ann.  Kept.,  1890; 
IV,  1893.  (Marbles.)  —  California :  11.  Eckel,  U.  S.  Geol.  Surv., 
Bull.  225  :  417, 1904.  (Slate.)  12.  Jackson,  Calif.  State  Min.  Bureau ; 
8th  Ann.  Kept. :  885,  1888.  (General.)  —  Colorado  :  13.  Lakes, 
Mines  and  Minerals,  XXII  :  29  and  62,  1901.  (General.)  — 14. 
Merrill,  Stones  for  Building  and  Decoration,  New  York,  1904. 
—  Georgia:  15.  McCallie,  Ga.  Geol.  Surv.,  Bull.  1,  1894.  (Marbles.) 
16.  Watson,  Ibid.,  Bull.  9-A,  1903.  (Granites  and  Gneisses.)  — 
Indiana:  17.  Hopkins,  Ind.  Geol.  and  Nat.  Hist.  Surv.,  20th  Ann. 
Kept. :  188, 1896.  18.  Siebenthal,  U.  S.  Geol.  Surv.,  19th  Ann.  Kept., 
VI :  292,  1898.  (Bedford  limestone.)  19.  Thompson,  Ind.  Geol.  and 
Nat.  Hist.  Surv.,  17th  Kept.:  19,  1891.  (General.)  — Maine :  20. 


BUILDING  STONES  91 

Merrill,  Stones  for  Building  and  Decoration.  Wiley  and  Sons,  New 
York,  1904.— Maryland:  21.  Matthews,  Md.  Geol.  Sure.,  11:125, 
1898.  (General.)— Massachusetts:  22.  Whittle,  Eng.  and  Min. 
Jour.,  LXVI  :  336,  1898.  (General.)  —  Michigan :  23.  Benedict, 
Stone,  XVII  :  153,  1898.  (Bayport  district.)  —  Missouri :  24.  Buck- 
ley and  Buehler,  Mo.  Bur.  Geol.  and  Mines,  Vol.  2,  1904.  — New 
Hampshire:  25.  Hitchcock,  10th  Census  U.  S.,  X  :  124,  1884.  — New 
York :  26.  Dale,  U.  S.  Geol.  Surv.,  19th  Ann.  Kept.,  Ill :  153,  1899. 
(Slate  belt.)  27.  Dickinson,  N.Y.  State  Museum,  Bull.  61,  1903. 
(Bluestone  and  other  Devonian  sandstones.)  28.  Smock,  N.  Y. 
State  Museum,  Bull.  3,  1888.  — Ohio:  29.  Orton,  Ohio  Geol.  Surv., 
V  :  578,  1884.  (General.) — Pennsylvania:  30.  Hopkins,  Penn. 
State  College,  Ann.  Kept.,  1895 ;  Appendix,  1897.  (Brownstones.) 
31.  Lesley,  Tenth  Census,  U.  S.,  X  :  146,  1884.  (General.)  — 
31  a.  South  Dakota:  Todd,  S.  Dak.  Geol.  Surv.,  Bull.  3  :  81,  1902. 
(General.)  —  Vermont:  32.  Perkins,  Kept,  of  State  Geologist  on 
Mineral  Industries  of  Vt.,  1899-1900,  1900,  1903-1904;  and  33.  Re- 
port on  Marble,  Slate,  and  Granite  Industries,  1898. —  Washington: 
.  34.  Shedd,  Wash.  Geol.  Surv.,  II :  3, 1902.  (General.)  —Wisconsin : 
35.  Buckley,  Wis.  Geol.  and  Nat.  Hist.  Surv.,  BuU.  IV,  1898. 
(General.)— Wyoming:  36.  Knight,  Eng.  and  Min.  Jour.,  LXVI: 
546,  1898. 

REFERENCES  ON  ONYX  MARBLE 

37.  DeKalb,  "Onyx  Marbles,"  Trans.,  Am.  Inst.  Min.  Engrs.,  XXV: 
557,  1896.  38.  Merrill,  Stones  for  Building  and  Decoration  (New 
York),  3d  ed.,  1904.  39.  Merrill,  Ann.  Kept.  U.  S.  Nat.  Mus. 
(Washington),  1895.  40.  Merrill,  Min.  Indus.,  Vol.  II,  "Onyx," 
1894. 


CHAPTER  TV 
CLAY 

Definition.  —  Clay,  which  is  one  of  the  most  widely  dis- 
tributed materials  and  one  of  the  most  valuable  commercially, 
may  be  denned  as  a  fine-grained  mixture  of  the  mineral  kao- 
linite  (the  hydrated  aluminum  silicate)  with  fragments  of 
other  minerals,  such  as  silicates,  oxides,  and  hydrates,  and 
also  often  organic  compounds  (sometimes  classed  as  col- 
loids), the  mass  possessing  plasticity  when  wet  and  becom- 
ing rock  hard  when  burned  to  at  least  a  temperature  of 
redness. 

Residual  Clays  (42). — Clays  are  derived  primarily  and 
principally  from  the  decomposition  of  crystalline  rocks, 
more  especially  feldspathic  varieties,  and  deposits  thus 
formed  will  be  found  overlying  the  parent  rock  and  grad- 
ing down  into  it.  From  its  method  of  origin  and  position 
it  is  termed  a  residual  clay  (Fig.  24). 

All  residual  clays  show  a  variable  amount  of  kaolinite  or  clay-substance. 
This  mineral,  which  is  white  in  color,  results  from  the  decomposition 
of  feldspar,  either  by  weathering,  or,  less  often,  by  the  action  of  volcanic 
vapors.  The  decay  of  a  large  mass  of  pure  feldspar  would  therefore 
yield  a  mass  of  white  clay,  but  in  most  instances,  the  feldspar  is  asso- 
ciated with  other  minerals,  such  as  quartz,  mica,  and  hornblende,  all 
of  which,  except  the  quartz,  decay  with  the  greater  or  less  rapidity, 
and  some  of  these,  such  as  the  hornblende,  may  likewise  yield  a 
hydrous  aluminum  silicate.  Any  ferruginous  minerals  in  the  rock  will, 
in  decomposing,  form  limonite,  which  stains  the 
92 


CLAY 


93 


Large  masses  of  pure  feldspar  are  rare,  but  feldspathic  rocks,  such 
as  granite  or  syenite,  are  more  common,  and  these  will  also  decompose 
to  clay;  but,  since  the  parent  rock  contains  other  minerals,  such  as 
quartz  or  mica,  these 
will  either  remain  as 
sand  grains  in  the 
clay,  or,  by  decom- 
position, will  form 
soluble  compounds, 
or  iron  stains.  The 
decay  of  many  rocks, 
for  example,  lime- 
stone and  shale  in  FIG.  24.  —  Section  showing  formation  of  residual  clay. 

After  Ries,  U.S.  Geol.  Surv.,  Prof.  Paper,  11:16. 
addition  to  the  crys- 
talline rocks,  produces  a  residuum  of  clay.     Kaolin  is  a  white-burning 
residual  clay,  but  it  is  rare. 

The  extent  of  a  deposit  of  residual  clay  will  depend  on  the  extent 
of  the  parent  rock  and  the  topography  of  the  land,  which  also  influences 
its  thickness.  On  steep  slopes  much  of  the  clay  may  be  washed  away 
and  residual  clays  are  also  rare  in  glaciated  regions,  for  the  reason  that 
they  have  been  swept  away  by  the  ice  erosion.  They  are  consequently 
wanting  in  most  of  the  Northern  states,  but  abundant  in  many  parts 
of  the  Southern  states,  where  the  older  formations  appear  at  the  surface. 

Sedimentary  Clays  (42).  — With  the  erosion  of  the  land 
surface  the  particles  of  residual  clay  become  swept  away 

to  lakes,  seas,  or 
the  ocean,  where 
they  settle  down 
in  the  quiet  water 
as  a  fine  alumin- 
ous sediment, 
After  f°rming  a  deposit 
of  sedimentary 


LOAMY  CLAY 

CLAY 

SAND 

SAND  AND  GRAVEL 


BED  ROCK' 


FIG.  25.  —  Section  of  a  sedimentary  clay 

Ries,  U.  S.  Geol.  Siirv.,  Prof.  Paper,  11:18 


clay  (Fig.  25).     Such  beds  are  often  of  great  thickness  and 


94  ECONOMIC   GEOLOGY   OF  THE   UNITED   STATES 

vast  extent.  With  the  accumulation  of  many  feet  of  other 
sediments  on  top  of  them,  they  often  become  solidated  either 
by  pressure  or  by  the  deposit  of  a  cement  around  the  grains. 
Consolidated  clay  is  termed  shale,  and  this  upon  being  ground 
and  mixed  with  water  often  becomes  as  plastic  as  an  uncon- 
solidated  clay. 

Sedimentary  clays  may  be  divided  into  the  following 
groups  according  to  their  mode  of  origin  and  form  of 
deposit. 

Marine  Clays.  —  Formed  by  the  deposition  on  the  ocean  floor  of 
the  finer  particles  derived  from  the  waste  of  the  land.  Such  ancient 
sea-bottom  clays  have  been  elevated  to  form  dry  land  in  all  the  con- 
tinents, in  many  cases  forming  consolidated  clay  strata,  but  elsewhere, 
especially  in  coastal  plains,  in  unconsolidated  condition.  Extensive 
clay  deposits  are  also  formed  in  protected  estuaries  and  lagoons  along 
the  sea  coast. 

Flood-plain  Clays.  —  Formed  by  the  deposition  of  clayey  sediment 
on  the  lowlands  bordering  a  river  during  periods  of  flood.  Layer 
upon  layer,  this  deposit  builds  a  flood  plain  often  of  great  extent 
and  depth.  Such  areas  of  flood-plain  clays  are  most  extensive  along 
the  greater  rivers  and  in  the  deltas  which  they  have  built  in  the 
sea. 

Lake  Clays.  —  Clay  is  deposited  on  the  bottom  of  many  lakes  and 
ponds  in  the  same  manner  as  on  the  ocean  bottom.  Where  the 
streams  bring  only  fine  particles  the  filling  of  a  lake  may  be  entirely 
of  clay.  Many  lakes  have  been  either  drained  or  completely  filled 
and  their  clays  therefore  made  available.  This  is  especially  true  of 
small,  shallow  lakes  formed  during  the  Glacial  Period. 

Glacial  Clays,  commonly  known  as  till  or  bowlder  clay,  a  rock  flour 
ground  in  the  glacial  mill  in  which  rock  fragments  were  worn  down  to 
clay  by  being  rubbed  together  or  against  the  bed  rock  over  which  the 
ice  moved.  When  the  ice  melted,  this  deposit  was  left  in  a  sheet  of 
varying  thickness  and  characteristics  over  a  large  part  of  the  area 
which  the  ice  covered. 


CLAY  95 

JEolian  Clays.  —  Wind  drifts  drive  clay  about,  and  in  favorable  posi- 
tions causes  its  accumulation  in  beds.  This  is  true  of  the  Chinese  loess, 
a  wind-blown  deposit  derived  from  residual  soils  and  drifted  about  in 
the  arid  climate  of  interior  China.  Some  at  least  of  the  loess  clays  of 
the  Mississippi  Valley  seem  to  have  a  similar  origin,  the  source  of  the 
clay  being  glacial  deposits ;  in  other  cases  loess  seems  to  be  a  water 
deposit  either  in  shallow  lakes  or  else  in  broad,  slowly  moving 
streams. 

Properties  of  Clay.  —  These  are  of  two  kinds,  physical 
and  chemical,  and  since  they  exercise  an  important  influence 
on  the  behavior  of  the  clay,  the  most  important  ones  may 
be  described. 

Chemical  Properties  (42). — The  number  of  common  ele- 
ments which  have  been  found  in  clays  is  great,  and  even 
some  of  the  rarer  ones  have  been  noted ;  but  in  a  given 
clay  the  number  of  elements  present  is  usually  small,  being 
commonly  confined  to  those  determined  in  the  ordinary 
chemical  analysis,  which  shows  their  existence  in  the  clay, 
but  not  always  the  state  of  the  chemical  combination. 
The  common  constituents  of  a  clay  are  silica,  alumina, 
ferric  or  ferrous  oxide,  lime,  magnesia,  alkalies,  titanic  acid, 
and  combined  water.  Organic  matter,  though  often  pres- 
ent, is  usually  in  small  amounts,  and  carbon  dioxide  is 
always  found  in  calcareous  clays.  The  effect  of  these 
may  be  noted  briefly. 

Silica  is  most  often  present  in  the  form  of  quartz  grains;  but  it 
may  also  be  contained  in  grains  of  undecomposed  minerals.  It  aids 
in  lowering  the  plasticity  and  shrinkage,  and  helps  to  increase  the 
refractoriness  at  low  temperatures.  A  clay  high  in  silica  (70  to  80 
per  cent)  is  usually  sandy.  Alumina,  which  is  most  abundant  in  white 
clays,  is  a  refractory  ingredient.  Iron  oxide  acts  as  a  coloring  agent  in 
both  the  raw  and  burned  clay,  small  quantities  coloring  a  burned  clay 


96     ECONOMIC  GEOLOGY  OF  THE  UNITED  STATES 

buff,  and  larger  amounts  (4  to  7  per  cent),  if  evenly  distributed,  turning 
it  red.  It  also  acts  as  a  flux  in  burning.  Whatever  the  iron  compound 
present  in  the  raw  clay  it  changes  to  the  oxide  in  burning.  Lime, 
magnesia,  and  alkalies  are  also  fluxing  ingredients  of  the  clay.  The 
combined  percentage  of  fluxing  impurities  is  small  in  a  refractory  clay, 
and  often  high  in  a  low  grade  one.  Lime,  if  present  in  considerable 
excess  over  the  iron,  will,  in  burning,  exert  a  bleaching  effect  on  the 
iron.  For  this  reason,  highly  calcareous  clays,  such  as  those  in  the 
Great  Lake  region,  burn  cream  or  buff.  When  lime  is  present  in  large 
amounts  it  also  causes  clay  to  soften  more  rapidly  in  firing  than  it 
otherwise  would. 

Chemically  combined  water  and  organic  matter  both  pass  off  at  a 
temperature  of  very  dull  redness  (450°  to  650°  C.).  Their  loss  leaves 
the  clay  temporarily  porous  until  fire  shrinkage  sets  in.  Titanic  acid, 
though  rarely  exceeding  1  per  cent,  acts  as  a  flux  at  high  tempera- 
tures at  least.  Sulphur  trioxide  is  rarely  present  in  sufficiently  high 
amounts  to  interfere  with  the  successful  burning  of  the  clay. 

Physical  Properties  (42). — These  include  plasticity,  ten- 
sile strength,  air  and  fire  shrinkage,  fusibility,  and  specific 
gravity. 

Plasticity  may  be  defined  as  the  property  which  clay  possesses  of 
forming  a  plastic  mass  when  mixed  with  water,  thus  permitting  it  to  be 
molded  into  any  desired  shape,  which  it  retains  when  dry.  This  is  an 
exceedingly  important  character  of  clay.  Clays  vary  from  exceedingly 
plastic,  or  "  fat  "  ones,  to  those  of  low  plasticity  which  are  "  lean  "  and 
sandy.  Plasticity  is  probably  due  in  part  to  fineness  of  grain,  and  in 
part  to  the  presence  of  colloids. 

Tensile  strength  is  the  resistance  which  a  mass  of  air-dried  clay  offers 
to  rupture,  and  is  probably  due  to  interlocking  of  the  particles.  Tests 
show  that  the  tensile  strength  of  clays  varies  from  15  to  20  pounds  per 
square  inch  up  to  400  pounds  or  more  per  square  inch.  Many  common 
brick  clays  range  from  100  to  200  pounds. 

Shrinkage,  is  of  two  kinds  —  air  shrinkage  and  fire  shrinkage.  The 
former  takes  place  while  the  clay  is  drying  after  being  molded,  and  i.s 


CLAY  97 

due  to  the  evaporation  of  the  water,  and  the  drawing  together  of  the 
clay  particles.  The  latter  occurs  during  firing,  and  is  due  to  a  com- 
pacting of  the  mass  as  the  particles  soften  under  heat.  Both  are 
variable.  In  the  manufacture  of  most  clay  products  an  average  total 
shrinkage  of  about  8  or  9  per  cent  is  commonly  desired.  Excessive  air  or 
fire  shrinkage  causes  cracking  or  warping  of  the  clay.  To  prevent  this 
a  mixture  of  clays  is  often  used. 

Fusibility  is  one  of  the  most  important  properties  of  clays.  When 
subjected  to  a  rising  temperature,  clays,  unlike  metals,  soften  slowly,  and 
hence  fusion  takes  place  gradually.  In  fusing,  the  clay  passes  through 
three  stages,  termed,  respectively,  incipient  fusion,  vitrification,  and 
viscosity. 

lu  the  lower  grades  of  clay,  that  is,  those  having  a  high  percentage 
of  fluxing  impurities,  incipient  fusion  may  occur  at  about  1000°  C., 
while  in  refractory  clays,  which  are  low  in  fluxing  impurities,  it  may 
not  occur  until  1300°  or  1400°  C.  is  reached.  The  temperature  interval 
between  incipient  fusion  and  vitrification  may  be  as  low  as  30°  C.  in 
calcareous  clays,  or  as  much  as  200°  C.  in  some  others.  The  recognition 
of  this  variation  is  of  considerable  practical  importance,  and  vitrified 
products,  such  as  paving  bricks  and  stoneware,  have  to  be  made  from 
a  clay  in  which  the  three  stages  of  fusion  are  separated  by  a  dis- 
tinct temperature  interval.  The  importance  of  this  rests  on  the  fact 
that  it  is  impossible  to  control  the  temperature  of  a  large  kiln  with- 
in a  few  degrees,  and  there  must  be  no  danger  of  running  into  a 
condition  of  viscosity  in  case  the  clay  is  heated  beyond  its  point  of 
vitrification. 

Specific  gravity  varies  commonly  from  about  1.70  to  2.30. 

Chemical  Composition.  —  As  might  be  expected  from  their 
diverse  modes  of  origin,  clays  vary  widely  in  their  chemical 
composition.  There  is  every  gradation  from  those  which, 
in  composition,  closely  resemble  the  mineral  kaolinite  to 
those,  like  ordinary  brick  clays,  in  which  there  is  a  high 
percentage  of  impurities.  This  variation  is  shown  in  the 
following  table :  — 


98 


ECONOMIC   GEOLOGY   OF   THE   UNITED   STATES 


•4 

*4 

3 

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jjS 

5 

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t& 

jf 

M  S 

s^ 

i 

Is- 

^  — 

Bfc 

o  «" 

Si 

IT 

Sj 

°i" 

J 

11 

!i 

g-g~ 

1 

-1 

t-i 

f| 

II 

i| 

-  ~ 

o  a 

|i 

|| 

B  55 

g  § 

t>  2 

M  1 

oo  H 

U!  ^ 

3 
M 

M 

M 

£ 

3*' 

£  •< 

1= 

5to 

o 

pq 

Si02 

46.3 

62.4 

45.7 

61.6 

52.52 

59.92 

67.84 

68.62 

67.78 

38.07 

64.64 

A1208 

39.8 

26.51 

40.61 

28.38 

31.40 

27.56 

21.83 

14.98 

16.29 

9.46 

14.62 

Fe208 

— 

1.14 

1.39 

.52 

2.34 

1.03 

1.57 

4.16 

4.57 

2.70 

5.69 

CaO 

— 

.57 

.45 

.46 

.4 

tr. 

.28 

1.48 

.6 

15.84 

5.16 

MgO 

— 

.01 

.09 

.36 

.42 

tr. 

.24 

1.09 

.727 

8.6 

2.90 

K20 

— 

.98 

2.82 

— 

\      61 

.64 

2.24 

3.36 

2.001 

2.76 

5.89 

Na20 

— 

— 

/ 

H20 

Moist 

13.9 

8.8 
.25 

8.98 
.35 

5.08 

1  12.42 

(9.70 
11.12 

5.90 

.80 

3.55 

2.78 

}  6.24 

2.49 

3.74 
.85 

Ti02 

Ti02 

MnO 

Ti02 

C02 

C02 

3.6 

.96 

.64 

.78 

20.46 

4.80 

MnO 

.76 

Classification  of  Clay.  —  It  is  possible  to  base  a  classifica- 
tion of  clays  either  on  origin,  chemical  and  physical  proper- 
ties, or  uses.  But  since  the  subdivisions  which  can  be  made 
are  not  sufficiently  distinct,  each  of  these  gives  rise  to  a  more 
or  less  unsatisfactory  grouping.  The  following  classifica- 
tion is  based  partly  on  mode  of  origin  and  partly  on  physical 
characters :  — 

1.  Residual  clays. 

A.  White-burning  (kaolins,  formed  from  feldspathic  rocks). 

B.  Colored-burning   (formed    from    igneous,   metamorphic,   and 

many  sedimentary  rocks). 

2.  Clastic,  or  mechanically  formed  clays. 

A.   Water  formed  (of  variable  extent,  depending  on  locality  and 
mode  of  deposit). 

a.  White-burning  (ball  and  paper  clays). 

b.  Colored-burning  (brick  and  pottery  clays). 


CLAY  99 

B.  Glacial  clays  (often  stony ;  all  colored-burning). 

C.  Wind-formed  clays  (some  loess). 

3.   Chemical  precipitates  (some  flint  clays). 

Kinds  of  Clays.  —  Many  kinds  of  clays  are  known  by 
special  names,  the  more  important  of  which  are  the 
following :  — 

Adobe.  A  sandy,  often  calcareous,  clay  used  in  the  west  and  south- 
west for  making  sun-dried  brick.  Ball  clay.  A  white-burning,  plastic, 
sedimentary  clay,  employed  by  potters  to  give  plasticity  to  their  mixture. 
Brick  clay.  Any  common  clay  suitable  for  making  ordinary  brick. 
China  clay.  A  term  applied  to  kaolin  (q.v.*).  Earthenware  clay.  Clay 
suitable  for  the  manufacture  of  common  earthenware,  such  as  flower 
pots.  Fire  clay.  A  clay  capable  of  resisting  a  high  degree  of  heat. 
Flint  clay.  A  peculiar  flintlike,  fire  clay,  which  when  ground  up  and 
wet  develops  no  plasticity.  Chemically  it  differs  but  little,  if  at  all, 
from  the  plastic  fire  clays.  Moreover,  the  two  often  occur  in  the  same 
bed,  either  in  separate  layers  or  irregularly  mixed.  Gumbo.  A  very 
sticky,  highly  plastic  clay,  occurring  in  the  central  states,  and  used  for 
making  burned -clay  ballast  (1).  Kaolin.  A  white-burning  residual 
clay,  employed  chiefly  in  manufacture  of  white  earthenware  and  por- 
celain. Loess.  A  sandy,  calcareous,  fine-grained  clay,  covering  thou- 
sands of  square  miles  in  the  Central  states,  and  of  wide  use  in  brick 
making.  Paper  clay.  Any  fine-grained  clay,  of  proper  color,  that  can 
be  employed  in  the  manufacture  of  paper.  Pipe  clay.  A  loosely  used 
term  applied  to  any  smooth  plastic  clay.  Strictly  speaking,  it  refers  to 
a  clay  suited  to  the  manufacture  of  sewer  pipe.  Pottery  clay.  Any 
clay  suitable  for  the  manufacture  of  pottery.  Retort  clay.  A  plastic 
fire  clay,  used  in  making  gas  retorts.  The  term  is  a  local  one  used 
chiefly  in  New  Jersey.  Sagger  clay.  A  loose  term  applied  to  clays 
employed  in  making  saggers ;  they  are  of  value  for  other  purposes  as 
well.  Stoneware  clay.  A  very  plastic  clay,  which  burns  to  a  vitrified 
or  stoneware  body.  Terra-colta  clay.  Clay  suitable  for  the  manufac- 
ture of  terra  cotta.  The  term  has  no  special  significance,  as  a  wide 
variety  of  clays  are  adapted  to  this  purpose. 


100          ECONOMIC   GEOLOGY   OF   THE   UNITED   STATES 

Geological  Distribution.  —  Clays  have  a  wider  distribution 
than  most  other  economic  minerals  or  rocks,  being  found  in 
all  formations  from  the  oldest  to  the  youngest.  The  pre- 
Cambrian  crystallines  yield  both  white  and  colored  residual 
clays,  usually  the  result  of  weathering,  though  more  rarely  of 
solfataric  action.  In  the  Paleozoic  rocks,  deposits  of  shale, 
and  sometimes  of  clay,  are  found  in  many  localities ;  and, 
since  they  are  usually  marine  sediments,  the  beds  are  often 
of  great  extent  and  thickness.  With  the  exception  of  cer- 
tain Carboniferous  deposits,  the  Paleozoic  clays  are  mostly 
impure.  The  Mesozoic  formations  contain  large  supplies  of 
clays  and  shale  suitable  for  the  manufacture  of  bricks,  terra 
cotta,  stoneware,  fire  brick,  etc. 

The  Pleistocene  clays  are  all  surface  deposits,  usually 
impure,  and  individually  of  limited  extent,  although  they 
are  thickly  scattered  all  over  the  United  States.  Their 
chief  value  is  for  brick  and  tile  making.  They  have  been 
accumulated  by  glacial  action,  on  flood  plains,  in  deltas,  or 
in  estuaries  and  lakes. 

Distribution  of  Clays  by  Kinds.  —  Kaolins  (59) .  —  Since 
kaolins  are  derived  only  from  crystalline  or  igneous  rocks, 
their  distribution  is  limited ;  indeed,  at  present  the  only 
deposits  worked  are  in  the  eastern  states.  Being  com- 
monly formed  by  the  weathering  of  pegmatite  veins,  kaolin 
deposits  have  great  length  as  compared  with  their  width, 
which  may  be  anywhere  from  5  to  300  feet.  Their  depth 
ranges  from  20  to  120  feet,  depending  on  the  depth  to 
which  the  feldspar  has  been  weathered. 

Quartz  and  white  mica  are  often  present  in  kaolin,  and  it  is 
then  frequently  necessary  to  put  the  clay  through  a  washing  process 


CLAY 


101 


to  remove  these  minerals.  The  difference  between  a  washed  and 
unwashed  kaolin  is  well  shown  by  the  two  following  analyses,  from 
which  it  is  seen  that  the  quartz  contents  have  been  considerably 
lowered,  and  that  the  washed  product  approaches  more  closely  to  the 
composition  of  kaolinite  :  — 


CRUDE  KAOLIN 

WASHED  KAOLIN 

SiO 

6°.40 

45.78 

ALO,    . 

26.51 

36.46 

Fe  O, 

1  14 

28 

FeO      

1.08 

CaO 

.57 

.50 

MgO    

Alkalies         

.01 
.98 

.04 
.25 

H  O 

880 

1340 

Moisture  

.25 

2.05 

Clay  substance  

100.66 
66.14 

99.84 
93.24 

North  Carolina  (44)  and  Pennsylvania  (50,  52)  are  the 
most  important  kaolin-producing  states,  but  deposits  are 
also  worked  in  Connecticut,  Maryland  (30),  and  Virginia 
(59).  It  is  known  to  occur  in  Alabama  (9).  All  of  these 
deposits  except  that  in  Connecticut  are  found  south  of 
the  limit  of  the  glacial  drift. 

The  output  from  the  American  deposits  is  insufficient 
to  supply  the  domestic  pottery  industry,  and  consequently 
many  thousand  tons  are  annually  imported  from  England. 
Since  this  can  be  brought  over  as  ballast,  it  is  possible  to 
put  it  on  the  American  market  at  a  low  price.  The  best 
grades  of  kaolin  sell  for  $10  to  $12  per  ton  at  Trenton, 
New  Jersey,  and  East  Liverpool,  Ohio,  these  being  the  two 
most  important  pottery  centers  of  this  country. 


102          ECONOMIC   GEOLOGY   OF   THE   UNITED   STATES 

Fire  Clays.  —  Fire  clays  are  found  in  the  rocks  of  all 
systems,  from  the  Carboniferous  to  the  Tertiary,  inclusive, 
with  the  exception  of  the  Triassic.  In  the  Lower  Creta- 
ceous of  New  Jersey  (42)  there  are  many  beds  of  refrac- 
tory clay,  variable  in  thickness  and  closely  associated  with 
beds  of  less  refractory  character.  They  not  only  support 
a  thriving  local  fire-brick  industry,  but  serve  also  as  a 
source  of  supply  for  factories  in  other  states.  Similar, 
but  less  extensive  and  less  refractory,  beds  occur  in  strata 
of  Cretaceous  Age  in  the  coastal  plain  of  Maryland  (30), 
Georgia  (17),  South  Carolina  (53),  and  Alabama  (9). 

The  most  extensive,  and  among  the  most  important,  beds 
of  fire  clay  are  those  found  in  the  Carboniferous  strata  of 
Pennsylvania  (48,  52),  Ohio  (46,  47),  Kentucky  (26,  27),  Indi- 
ana (20),  and  Illinois  (19).  Those  of  the  first  two  named 
states  are  on  the  average  the  most  refractory.  Here  the 
fire  clays  are  usually  found  underlying  coal  seams  and  often 
at  well-marked  horizons,  especially  in  the  Upper  Productive 
Measures. 

The  section  given  in  Fig.  2  is  fairly  representative  of 
their  mode  of  occurrence. 

Those  of  Indiana  and  Illinois  are  so  placed  that  one  mine 
shaft  is  often  used  for  extracting  coal,  fire  clay,  stoneware 
clay,  and  shale. 

The  beds  of  refractory  clay,  found  in  the  Carbon- 
iferous strata  near  St.  Louis  (38),  are  not  only  used  in  the 
manufacture  of  fire  brick,  but  are,  in  some  cases,  found 
suitable,  after  washing,  for  mixture  with  imported  Ger- 
man clays  for  the  manufacture  of  glass  pots.  The  Ter- 
tiary strata  of  Missouri  also  supply  some  refractory 
clays. 


PLATE  IX 


CLAY  103 

Fire  clays  are  found  in  the  Black  Hills  of  South  Dakota  (54),  in 
the  Laramie  beds  of  Colorado  (13-15),  and  in  California  (12) ;  but,  except- 
ing near  Denver,  where  used  for  making  fire  brick  and  assayer's  appa- 
ratus, these  deposits  are  as  yet  slightly  developed. 

Pottery  Clays.  —  Under  this  heading  are  included  several 
grades  of  clay,  the  kaolins,  already  described,  being  the 
purest  and  best  suited  to  the  manufacture  of  high  grades 
of  pottery. 

A  second  grade  of  pottery  clay,  the  ball  clay,  is  of  limited 
distribution  in  the  United  States.  A  small  quantity  is 
found  in  the  Cretaceous  (PL  IX)  of  New  Jersey  (42), 
and  a  much  larger  amount  in  the  Tertiary  of  western 
Kentucky  (26, 27)  and  Tennessee  (55),  and  southeastern 
Missouri  (38)  and  Florida  (59).  As  in  the  case  of  kaolin,  the 
domestic  supply  is  not  sufficient  to  meet  the  demand,  and 
large  quantities  of  ball  clay  are  imported  from  England. 

Stoneware  clays  form  a  third  grade  of  pottery  clays. 
Being  usually  of  at  least  semi-refractory  character,  their 
distribution  is  essentially  coextensive  with  that  of  fire 
clays;  indeed,  the  two  are  often  dug  from  the  same  pit  or 
mine.  Large  quantities  are  obtained  in  New  Jersey  (42), 
western  Pennsylvania  (48),  and  eastern  Ohio  (47). 

Stoneware  clays  usually  in  the  same  area  as  the  fire  clays  are  also 
obtained  in  Illinois  (19),  Indiana  (20),  Kentucky  (26),  Tennessee  (55), 
Georgia  (17),  Alabama  (9),  and  Texas  (56) ;  and  they  occur  also  in 
Missouri  (38),  Iowa  (22),  Colorado  (14),  and  California  (12),  although 
little  is  known  about  these  deposits. 

Many  of  the  Pleistocene  surface  clays  in  various  states 
are  sufficiently  dense-burning  to  be  used  locally  by  small 
stoneware  factories. 


104          ECONOMIC    GEOLOGY    OF    THE    UNITED    STATES 

Brick  and  Tile  Clays  (59) .  —  None  of  our  states  lack  an 
abundant  supply  of  good  brick  and  tile  clays,  and  in  many 
areas  there  are  extensive  deposits  near  the  large  markets, 
and  often  near  tide  water.  In  such  cases  the  clay  beds 
are  exploited  to  an  enormous  extent. 

In  the  northeastern  states  the  Pleistocene  surface  clays 
are  found  almost  everywhere  in  great  abundance,  and  are 
made  use  of  in  many  places,  especially  near  the  large  cities. 

In  the  Middle  Atlantic  states  Columbian  loams  and  clay 
marls  are  an  important  source  of  brick  material. 

In  Ohio,  Illinois,  and  Indiana  Pleistocene  clays,  in  part 
of  glacial,  and  in  part  of  flood-plain  origin,  are  much  used 
for  brick  and  tile.  Impure  Paleozoic  shales  are  also  used 
in  places,  especially  in  the  manufacture  of  vitrified  paving 
brick,  thousands  of  which  are  made  annually  in  Ohio. 
Northern  Illinois,  Michigan,  and  Wisconsin  draw  their  main 
supply  of  brick  clays  from  the  calcareous  lake  deposits. 

Although  glacial  clays  and  flood-plain  deposits  are  much 
used  in  the  states  west  of  the  Mississippi,  the  loess  which 
occurs  over  a  wide  area  is  probably  even  more  important 
as  a  source  of  brick,  while  in  the  southwestern  states  loess 
and  adobe  are  important.  Residual  clays,  river  silts,  glacial 
clays,  and  other  forms  of  clay  are  employed  in  brick  making 
along  the  Pacific  coast. 

Miscellaneous  Clays  of  Importance.  —  Paper  clays  of  good  quality  are 
much  sought  for  by  paper  manufacturers.  At  present  the  best  ones 
are  obtained  from  the  Potomac  formation  of  North  Carolina.  A  small 
amount  of  glasspot  clay  (48),  comes  from  western  Pennsylvania  and 
eastern  Missouri;  but  our  chief  supply  is  imported.  Terra-cotta  clays 
are  obtained  from  the  same  areas  that  supply  fire  clays,  New  Jersey 
being  the  principal  producer. 


CLAY 


105 


Uses  of  Clay.  —  So  few  people  have  even  an  approxi- 
mate idea  of  the  uses  to  which  clays  are  put  that  it  seems 
desirable  to  call  attention  to  them  briefly.  In  the  following 
table  an  attempt  has  been  made  to  do  this : 1  — 

Domestic.  —  Pottery  of  various  grades;  Polishing  brick,  often  known  as 
bath  bricks;  Fire  kindlers;  Majolica  stoves. 

Structural.  —  Brick;  Tiles  and  Terra  cotta;  Chimney  pots ;  Chimney  flues ; 
Door  knobs ;  Fireproofing;  Copings;  Fence  posts. 

Hygienic.  —  Closet  bowls  ;  Sinks,  etc. ;  Sewer  pipe  ;  Ventilating  flues  ; 
Foundation  Blocks;  Vitrified  bricks. 

Decorative.  —  Ornamental  pottery ;  Terracotta;  Majolica;  Garden  furniture. 

Minor  Uses.  —  Food  adulterants;  Paint  filler;  Paper  filling ;  Electrical 
insulations;  Pumps;  Filling  cloth;  Scouring  soap;  Packing  horses' 
hoofs ;  Chemical  apparatus ;  Condensing  worms ;  Ink  bottles ;  Ultra- 
marine manufacture;  Emery  wheels. 

Refractory  Wares.  —  Crucibles  and  other  assaying  apparatus ;  Refractory 
bricks  of  various  patterns ;  Glass  pots. 

Engineering  Work.  —  Puddle;  Portland  cement;  Railroad  ballast;  Water 
conduits;  Turbine  wheels. 

Production  of  Clay.  —  Owing  to  the  fact  that  clays  are 
usually  manufactured  by  the  producer,  it  is  necessary  to 
give  the  value  of  the  product,  no  record  being  kept  of 
value  of  the  raw  material. 

VALUE  OF  CLAY  PRODUCTS  IN  UNITED  STATES,  1901-1903 


1901 

1902 

1903 

Ohio     .     .          .     . 

$21,574,985 

$24,249,748 

$25  208  128 

Pennsylvania      .     . 
New  Jersey   .     .     . 
Illinois      .... 
New  York     .     .     . 
Indiana     .... 
Others  

15,321,742 
11,681,878 
9,642,490 
8,291,718 
4,466,454 
39,232,320 

17,833,425 
12,613,263 
9,881,840 
8,414,113 
5,283,733 
44,293,409 

18,847,324 
13,416,939 
11,190,797 
9,208,252 
5,694,625 
47,396,583 

Total     .... 

$110,211,587 

$122,169,531 

$130,962,648 

i  Table  compiled  by  E.  T.  Hill  and  modified  by  H.  Hies. 


106          ECONOMIC   GEOLOGY   OF  THE  UNITED   STATES 
LEADING  STATES  IN  PRODUCTION  IN  1903 


PEE  CENT  OF  TOTAL 

Common  brick  

Pennsylvania   . 

12.2. 

Pennsylvania   . 

19.7 

Vitrified  brick       

Ohio    .... 

28.8 

Ornamental  brick      .... 
Fire  brick 

Ohio    .... 

4.7 
464 

Drain  tile              

Ohio    .... 

24.7 

Ohio    .... 

386 

Terra  cotta  

Illinois     . 

25.6 

New  Jersey  . 

46.3 

Hollow  tile  and  block  .     .     . 
Tile,  not  drain     

Ohio   .... 
Ohio   .... 

44.9 
30.5 

REFERENCES  OW  CLAY 

TECHNOLOGY  AND  PROPERTIES.  1.  Bain,  Min.  Indus.,  VI :  157,  1898. 
(Clay  ballast.)  2.  Barber,  The  Pottery  and  Porcelain  of  the  United 
States,  2d  ed.,  N.  Y.,  1901  (G.  P.  Putnam's  Sons),  $5.00. 
3.  Bourry,  Treatise  on  Ceramic  Arts,  N.  Y.  (Van  Nostrand  &  Co.), 
London  (Scott  Greenwood  &  Co.),  1901.  4.  Bischof,  Die  Feuer- 
festen  Thone,  2d  ed.,  Leipzig,  1895  (Quandt  &  Handel),  12  Mks. 
5.  Branner,  Bibliography  of  Clays  and  the  Ceramic  Arts,  U.  S.  Geol. 
Surv.,  Bull.  143,  Washington,  1896.  7.  Davis,  A  Practical  Treatise 
on  the  Manufacture  of  Bricks,  Tiles,  and  Terra  Cotta,  2d  ed.,  Philadel- 
phia, $5.00.  8.  Wheeler,  Vitrified  Paving  Brick,  Indianapolis,  1895, 
(Clayworker  Pub.  Co.),  fl.OO.  Many  excellent  papers  in  Transac- 
tions American  Ceramic  Society,  Vols.  1-6  of  which  have  appeared. 
See  also  Nos.  22,  30,  42,  43  for  general  properties  and  technology. 

AREAL  REPORTS.  —  Alabama:  9.  Smith  and  Ries,  Ala.  Geol.  Surv., 
Bull.  6,  1900.  (General.)  — Arkansas:  10.  Branner,  Ark.  Geol. 
Surv.,  Rept.  for  1888.  (Many  analyses.)  11.  Also  Amer.  Inst.  Min. 
Engrs.,  Trans.  XXVII:  42,  1898.  (S.  W.  Ark.)  —  California : 
12.  Johnston,  Calif.  State  Mineralogist,  9th  Ann.  Rept.:  287,  1890. 
(General.)  See  also  scattered  notices  in  other  annual  reports. — 
Colorado:  13.  Eldridge,  U.  S.  Geol.  Surv.,  Mon.  XXVII,  1896. 
(Denver  Basin.)  14.  Geijsbeek,  Clay  Worker,  XXXVI :  424,  1901. 
(General.)  15.  Ries,  Amer.  Inst.  Min.  Engrs.,  XXVII :  336,  1898. 
(Clays  and  Clay  Industry.)  —  Delaware :  16.  Booth,  Geol.  of  Dela- 


CLAY  107 

ware:  94  and  106, 1841.  — Georgia :  17.  Ladd,  Ga.  Geol.  Surv.,  Bull. 
6  A.,  1898.  (Cretaceous  clays.)  18.  Spencer,  Ga.  Geol.  Surv.,  Paleo- 
zoic Group :  276,  1893.  (N.  W.  Ga.)  —  Illinois  :  19.  Many  scattered 
references  in  volumes  on  Economic  Geology  of  Illinois  Geol.  Survey, 
Resume  of  these  in  TJ.  S.  Geol.  Sutv.,  Prof.  Pap.  11,  1903.  — Indiana: 
20.  Blatchley,  Ind.  Dept.  Geol.  and  Nat.  Hist.,  20th  Ann.  Kept. :  23, 
1896.  (Carboniferous  clays.)  21.  Same  author,  22d  Ann.  Kept.: 
105,  1898.  (X.  W.  Ind.)  Scattered  references  in  other  annual  re- 
ports. —  Iowa :  22.  Beyer,  Williams,  and  Weems,  la.  Geol.  Survey, 
XIV:  29,  1904.  —  Kansas :  23.  Prosser,  U.  S.  Geol.  Surv.,  Mineral 
Resources,  1892:  731,  1893.  24.  See  also  Reports  on  Mineral 
Resources  of  Kansas,  Kas.  Geol.  Survey,  1897-1901.  —  Kentucky: 
25.  Crump,  Eng.  and  Min.  Jour.,LXVI:  190,  1898.  26.  Ries,  U.  S. 
Geol.  Surv.,  Prof.  Pap.  11,  1903.  27.  Many  analyses  in  Ky.  Geol. 
Surv.,  Chem.  Rept.  A,  pts.  1,  2,  and  3,  1885, 1886, 1888.— Louisiana: 
28.  Clendenin,  Eng.  and  Min.  Jour.,  LXVI:  456,  1898.  29.  Ries, 
Preliminary  Report  on  Geology  of  La.,  I:  264,  1899.  — Maryland: 

30.  Ries,  Md.  Geol.  Surv.,  IV,  Pt.  Ill:  205,  1902.  —  Massachusetts : 

31.  Crosby,  Technol.  Quart.,  Ill :  228,  1890.    (Kaolin  at  Blandford.) 

32.  Shaler,  Woodworth,  and  Marbut,  U.  S.  Geol.  Surv.,  17th  Ann. 
Rept.,  1 :  957, 1896.  (R.  I.  and  S.  E.  Mass.)  33.  Whittle,  Eng.  and  Min. 
Jour.,  LXVI:  245,  1898.  —  Michigan :   34.  Ries,  Mich.  Geol.  Surv., 
VIII :  Pt.  I,  1903.    (Clays  and  shales.)  —  Minnesota :  35.  Berkey, 
Amer.  Geol.,  XXIX :  171,  1902.  (Origin  and  distribution.)   36.  Win- 
chell,  Minn.  Geol.  Surv.,  Misc.  publications,  No.  8,  1881.     (Brick 
clays.)  —  Mississippi :  37.  Eckel,  U.  S.  Geol.  Surv.,  Bull.  213 :  382, 
1903.   (N.W.  Miss.)— Missouri:  38.  Wheeler,  Mo.  Geol.  Surv.,  XI, 
1896.    (General.)  — Nebraska:  39.  Neb.  Geol.  Surv.,  I:  202,  1903.— 
New  Hampshire :  40.  Hitchcock  and  Upham,  Report  on  Geology  of 
New  Hampshire,  V:  85,  1878.  — New  Jersey:   41.  Cook,  N.  J.  Geol. 
Surv.,  1878.     (Special  Report  on  Clays.)     42.  Kummel,  Ries,  Knapp, 
N.  J.  Geol.  Surv.,  Final  Reports,  VI,  1904.  — New  York:  43.  Ries, 
N.  Y.  State  Museum,  Bull.  35,  1900.     (General.)  —North  Carolina: 
44.  Ries,  N.  Ca.  Geol.  Surv.,  Bull.  13,  1897.      (General.)  —  North 
Dakota :  45.  Babcock,  N.  D.  Geol.  Surv.,  1st  Rept. :  27.     (General.) 
—  Ohio :   46.  Orton,  Ohio  Geol.  Surv.,  VII :  45,  1893.      (Geology.) 

47.  Orton,  Jr.,   Ibid.,  p.  69.      (Clay  industries.)  —  Pennsylvania  : 

48.  Hopkins,  Pa.  State  College,  Ann.  Repts.  as  follows,  1897,  Ap- 
pendix.     (W.   Pa.)      49.  Ibid.,  Append,  to  Rept.  for   1899-1900. 
(Philadelphia  and  vicinity).      50.   Ibid.,  1898-1899.      (S.  E.  Pa.) 
51.  Many  analyses  in  2d  Pa.  Geol.'  Surv.,  Rept.  MM. :  257,  1879, 
and  scattered  references  in  Repts.  H  5,  H  4,  C  4,  C  5,  etc.     52.  Re'- 
sume  in  U.  S.  Geol.  Surv.,  Prof.  Pap.  11 :  208, 1903.  —  South  Carolina : 


108    ECONOMIC  GEOLOGY  OF  THE  UNITED  STATES 

53.  Sloane,  Bull.  I,  S.  Car.  Geol.  Surv.  (S.  Car.)  —  South  Dakota :  54. 
Todd,  S.  D.  Geol.  Surv.,  Bull.  3:  101.  —  Tennessee :  55.  Eckel, 
U.  S.  Geol.  Surv.  Bull.,  213  : 382, 1903.  (W.  Tenn.)  —  Texas :  56.  See 
county  reports  issued  by  First  Geol.  Survey. — United  States:  57.  Hill, 
U.  S.  Geol.  Surv.  Min.  Res.  1891 :  474,  1893.  58.  Ries,  U.  S.  Geol. 
Surv.  17th  Ann.  Rept.,  Ill :  845,  1896.  (Pottery  Clays.)  59.  Ries, 
U.  S.  Geol.  Surv.,  Prof.  Pap.  11,  1903.  (Clays  east  of  Mississippi 
River.)  —  Vermont :  60.  Nevius,  Eng.  and  Min.  Jour.  LXIV  :  189, 
1897.  (Kaolin.)  61.  Ries,  U.  S.  Geol.  Surv.,  Prof.  Pap.  11 :  133, 
1903.  — Washington:  62.  Landes,  Wash.  Geol.  Surv.,  I:  173,  1902. 
(General.)  — Wisconsin:  63.  Buckley,  Wis.  Geol.  and  Nat.  Hist. 
Surv.,  Bull.  7,  Pt.  I,  Eco.  Series  4,  1901.  (General.)  64.  Forth- 
coming bulletin  by  Ries.  — Wyoming :  65.  Knight,  Wyo.  Experiment 
Station,  Bull.  14, 1893.  (General.) 


CHAPTER  V 


LIME  AND  CALCAREOUS  CEMENTS 

Composition  of  Limestones  (35).  —  Limes  and  calcareous 
cements  form  an  important  class  of  economic  products, 
obtained  from  limestones  by  heating  them  to  a  tempera- 
ture ranging  from  that  of  decarbonation  to  clinkering. 
The  term  limestone  is  applied  to  one  of  the  main  divi- 
sions of  the  stratified  rocks  so  widely  distributed,  both 
geologically  and  geographically,  and  formed  under  such 
different  conditions,  that  its  composition  varies  greatly, 
this  range  of  variation  becoming  appreciable  from  an 
inspection  of  the  following  table,  which  contains  a  few 
selected  types : l  — 

TABLE  OF  LIMESTONE  ANALYSES,  INCLUDING  THE  MINERALS 
CALCITE  AND  DOLOMITE 


CaC08 

MgC08 

SiO2 

A1208 

Fe208 

HaO 

1.  Calcite     .... 
2.  Dolomite      .     .     . 
3.  White    limestone, 
Adams,  Mass.    . 
4.  Limestone,  Lehigh 
Valley    district, 
pa 

100.00 
54.35 

99.30 
8800 

45.65 
.49 

400 

.63 
5  87 

.55 
1 

59 

5.  Limestone,  Coplay, 
Pa  

67.14 

2.90 

18.34 

7 

49 

3.92 

Kemp,  "  Handbook  of  Rocks.' 
109 


110 


ECONOMIC   GEOLOGY   OF  THE  UNITED   STATES 


CaCO8 

MgC08 

SiOa 

A1208 

Fe-A. 

H2O 

6.  Limestone,     Cum- 

berland, Md.     . 

41.80 

8.60 

24.74 

16.74 

6.30 

7.  Dolomite,  Pleasant- 

ville,  N.Y.     .    . 

59.84 

36.80 

2.31 

.40 

.25 

8.  Magnesian     lime- 

stone, Rosendale, 

N.Y  

45.91 

26.14 

15.37 

11.38 

1.20 

1 

From  this  table  it  will  be  seen  that  limestones  vary  from 
rocks  composed  almost  entirely  of  carbonate  of  lime,  or  of 
carbonate  of  lime  and  carbonate  of  magnesia,  to  others 
which  are  high  in  clayey  or  siliceous  impurities.  The 
presence  of  such  impurities  in  large  quantity  usually 
imparts  an  earthy  appearance  to  the  limestone,  and  some- 
times even  gives  it  a  shaly  structure. 

Marked  variations  in  composition  may  at  times  be  found 
even  in  a  single  quarry,  while  in  other  cases  a  limestone 
formation  may  show  remarkable  uniformity  of  composition 
over  a  wide  area. 

Changes  in  Burning  (8,  35).  —  When  limestones  are  cal- 
cined or  "burned"  to  a  temperature  sufficiently  high  to 
drive"  off  volatile  constituents,  such  as  carbon  dioxide, 
water,  and  sulphur  (in  part),  or,  in  other  words,  to  the 
point  of  decarbonation,  the  rock  is  left  in  a  more  or  less 
porous  condition.  If  heated  to  a  still  higher  temperature, 
the  rock  clinkers  or 'fuses  incipiently,  but  the  temperature 
of  clinkering  depends  on  the  amount  of  siliceous  and  clayey 
impurities  in  the  rock. 

Lime  (5,  8). — Limestone  free  from  or  containing  but  a 
small  percentage  of  argillaceous  impurities  is,  by  decarbona- 


LIME   AND   CALCAREOUS   CEMENTS  111 

tion,  changed  to  quicklime,  a  substance  which  has  a  high 
affinity  for  water,  and  which,  when  mixed  with  water, 
"slakes,"  forming  a  hydrate  of  lime.  This  change  is 
accompanied  by  the  evolution  of  heat  and  by  swelling, 
and  this  action  becomes  the  more  marked  the  higher  the 
percentage  of  lime  carbonate  in  the  rock,  for  the  slaking 
activity  is  retarded  by  the  presence  of  magnesium  carbon- 
ate, and  especially  by  argillaceous  impurities.  Limes  have, 
therefore,  been  divided  into  "fat"  limes  and  "meager" 
limes,  depending  on  the  rapidity  with  which  they  slake 
and  the  amount  of  heat  they  develop  in  doing  so  (5). 

Hydraulic  Cements.  —  With  an  increase  in  clayey  and 
siliceous  impurities,  the  burned  rock  shows  a  decrease  in 
slaking  qualities,  and  develops  hydraulic  properties,  or  sets 
when  mixed  with  water,  and  even  under  the  same.  Products 
of  this  type  are  termed  cements,  and  owe  their  hydraulic 
properties  to  the  formation  during  burning  of  silicates  and 
aluminates  of  lime.  On  mixing  the  burned  ground  rock 
with  water,  these  take  up  the  latter  and  crystallize,  thereby 
producing  the  set  of  the  cement. 

Hydraulic  cements  can  be  divided  into  the  following 
classes :  Pozzuolano  cements,  hydraulic  limes,  natural  ce- 
ments, and  Portland  cements. 

Pozzuolano  Cements  (2,  9,  41).  —  These  are  produced  from 
an  uncalcined  mixture  of  slaked  lime  and  a  silico-aluminous 
material,  such  as  volcanic  ash  or  blast-furnace  slag. 

This  process  was  known  to  the  ancients,  and  is  named 
from  its  early  use  around  Pozzuolano,  Italy.  The  composi- 
tion of  an  Italian  Pozzuolano  earth  may  vary  between  the 
following  limits  (9):  SiO2,  52-60;  A12O3,  9-21;  Fe2O3, 


112 


ECONOMIC    GEOLOGY   OF   THE   UNITED   STATES 


5-22;  CaO,  2-10;  MgO,  up  to  2;  alkalies,  3-16;  H2O, 
up  to  12. 

The  manufacture  of  slag  cement  is  now  carried  on  at 
several  localities  in  the  United  States,  and  is  a  growing 
industry  (2). 

Hydraulic  Limes  (9)  are  formed  by  burning  a  siliceous 
limestone  to  a  temperature  not  much  above  that  of  decar- 
bonation.  Owing  to  the  high  percentage  of  lime  carbon- 
ate, considerable  free  lime  appears  in  the  finished  product. 
Hydraulic  limes  generally  have  a  yellow  color,  and  a  gravity 
of  about  2.9.  They  slake  and  set  slowly,  and  have  little 
strength  unless  mixed  with  sand.  This  class  is  of  little  im- 
portance in  the  United  States,  but  much  more  so  in  Europe. 

Natural  Cements  (1,  8,  9,41). — These,  known  also  as  Roman 
cement,  quick-setting  cement,  and  Rosendale  cement,  are 
made  by  burning  a  silico-aluminous  limestone  (containing 
from  15  to  40  per  cent  clayey  impurities)  at  a  temperature 
between  decarbonation  and  clinkering.  The  product  shows 
little  or  no  free  lime.  The  following  analyses  will  give 
some  idea  of  the  range  in  composition  of  natural  cement 
rocks  quarried  in  the  United  States:  — 

ANALYSES  OF  CERTAIN  AMERICAN  CEMENT  ROCKS 


CaCO3 

MgC08 

Si02+ 
INSOL. 

FeaOg 

A1208 

ALKA- 
LIES 

H20 

UN- 

DET. 

Rosendale,  N.Y. 

45.91 

26.14 

15.37 

11. 

38 

1. 

20 

Utica,  111.  .     .     . 

42.25 

31.98 

21.12 

1. 

12 

1.07 

2.46 

Milwaukee,  Wis. 

45.54 

32.46 

17.56 

3.03 

1.41 

Fort  Scott,  Kas. 

65.21 

10.65 

15.21 

4.56 

4.37 

Cement,  Ga.  .     . 

43.50 

22.00 

22.10 

1.80 

5.45 

.22 

4.95 

Coplay,  Pa.    .     . 

67.14 

2.90 

18.34 

7. 

49 

.19 

3.94 

LIME   AND   CALCAKEOUS   CEMENTS 


113 


Natural  cements  differ  from  lime  in  possessing  hydraulic 
properties,  and  refusal  to  slake  unless  ground  very  fine. 
They  differ  from  Portland  cements  in  lighter  weight,  lower 
temperature  of  burning,  quicker  set,  lower  ultimate  strength, 
and  greater  latitude  of  composition.  Magnesia  is  not  re- 
garded as  a  detrimental  impurity  in  natural  cements  as  it 
is  in  Portland  cement. 

The  following  are  some  analyses  of  the  burned  material :  — 

ANALYSES  OF  SOME  NATURAL  ROCK  CEMENTS 


CaO 

MgO 

Si02 

A1208 

Fe208 

Na2O,K2O 

IGNITION 

Natural  rock  cement, 

Rosendale,  N.Y.      . 

34.38 

18 

30.5 

6.84 

2.42 

3.98 

3.78 

Natural  rock  cement, 

Akron,  N.Y.       .     . 

40.68 

22 

22.62 

7.44 

1.40 

2.23 

3.63 

Natural  rock  cement, 

Cumberland,  Md.    . 

43.97 

2.21 

22.38 

11.71 

2.29 

9. 

2.44 

Roman    cement,    Rii- 

dersdorf,  Germany  . 

56.45 

4.84 

27.88 

6.19 

4.64 

Portland  Cement  (4,  6,  7, 10,  41).  — This  term  is  applied  to 
artificial  mixtures  of  clay  and  lime  rock,  which  are  burned 
to  a  temperature  of  clinkering.  Portland  cement  was  first 
made  by  Joseph  Apsdin,  of  Leeds,  England,  who  desired 
to  make  an  artificial  cement  that  would  replace  natural 
hydraulic  cements.  It  received  its  name  because  it  hard- 
ened under  water  to  a  mass  resembling  the  Portland  stone 
of  England. 

The  three  essentials  for  Portland  cement  are  lime,  silica, 
and  alumina,  and  it  is  consequently  necessary  to  use  raw 
materials  supplying  these  three  substances  in  the  proper 
quantities.  This  is  in  all  cases  done  by  artificial  mixture, 


114          ECONOMIC   GEOLOGY   OP  THE   UNITED   STATES 

and  many  of  the  so-called  "natural"  Portland  cements 
used  in  the  United  States  are  not  strictly  such.  The  fol- 
*  lowing  six  combinations  of  materials  are  at  present  used 
in  the  manufacture  of  true  Portland  cement  in  the  United 
States :  marl  and  clay ;  limestone  and  clay,  or  shale ; 1  chalk 
and  clay;  pure  limestone  and  argillaceous  limestone;  alkali 
waste  and  clay;  limestone  and  slag. 

In  the  first  four  of  these  combinations  it  is  evident  that  the  sub- 
stances first  named  supply  the  lime  and  the  second  the  silica  and 
alumina.  In  the  fourth  the  argillaceous  limestone  supplies  some  lime, 
as  well  as  the  silica  and  alumina.  The  nature  of  the  raw  materials 
chosen  depends  to  a  large  degree  on  the  location  of  the  plant,  whether 
in  a  limestone  or  a  marl  producing  region.  Where  both  of  these  raw 
materials  are  available,  as  in  parts  of  New  York,  questions  of  manipu- 
lation in  the  process  of  manufacture  govern  the  selection  of  one  or 
the  other. 

Marls,  for  example,  though  easier  to  excavate  and  reduce  than  lime- 
stones, contain  so  much  more  organic  matter  and  water  than  limestones 
that  they  are  more  expensive  to  handle  and  prepare.  Marl  beds  are 
likewise  apt  to  be  of  limited  extent  and  irregular,  while  limestone 
beds  are,  so  far  as  the  needs  of  a  manufacturing  plant  are  concerned, 
practically  limitless. 

Comparing  clay  and  shale,  the  former  is  often  easier  to  excavate, 
but,  on  account  of  the  water  it  contains,  has  to  be  dried  before  it  can 
be  ground  and  mixed.  The  fossils  in  shales  are  sometimes  an  impor- 
tant source  of  calcium  carbonate,  and  then  careful  grinding  and  mixing 
is  necessary  to  bring  about  a  uniform  distribution  of  the  lime  through 
the  mass.  Shale  is,  however,  used  by  only  a  few  works. 

Argillaceous  limestone,  mixed  with  a  much  smaller  quantity  of  purer 
limestone,  as  in  Pennsylvania  and  New  Jersey,  is  superior  to  a  lime- 
stone and  clay  mixture,  because  less  thorough  mixing  and  fine  grinding 
are  required.  In  such  cements,  even  when  grinding  and  mixing  are 

1  It  is  probable  that  the  refuse  of  many  slate  quarries  could  also  be  used 
in  place  of  shale. 


LIME   AND   CALCAREOUS   CEMENTS 


115 


incompletely  done,  the  particles  of  argillaceous  limestone  so  closely 
resemble  the  proper  mixture  in  chemical  composition  as  to  affect  the 
result  but  little. 

The  following  table  gives  the  analyses  of  some  of  the 
raw  materials  used  in  manufacture  of  Portland  cement:  — 

ANALYSES  OF  RAW  MATERIALS  USED  FOR  PORTLAND  CEMENT 


LOCALITY 

MATERIAL 

SiO2 

A1208 

Fea08 

CaC08 

MgCOa 

H2O  + 
OKG. 
MATTER 

MlSCEL. 

Calc.  shale 

Lehigh 

or 

CaSO4 

Valley, 

cement  rock 

15.40 

4.26 

1.38 

74.66 

2.66 

1.88 

.86 

Penn. 

Limestone 

5.87 

1.59 

88.00 

4.00 

Mixture 

13.97 

5.07|  1.88 

74.1 

2.04 

1.82 

Glens 

CaO 

MgO 

S03 

Limestone 

3.3 

1.3 

52.15 

1.58 

.3 

Falls, 
N.Y. 

CaO 

MgO 

S03 

Clay 

55.27 

28.15 

5.84 

2.25 

8.37 

.12 

Warners, 

/Marl 

.26 

.10 

94.39 

.38 

4.64 

N.Y. 

I  Clay 

40.48 

20.95 

25.80 

.99 

8.50 

Insol. 

CaSO< 

Sandusky, 

Marl 

1.28 

1.72 

92.70 

.50 

1.13 

2.06 

Ohio 

CaO 

MgO 

Clay 

64.70 

11.9 

9.9 

.90 

.70 

11.9 

White 

{  Chalk 

7.97 

1.09 

88.64 

.73 

Cliffs, 

CaO 

MgO 

Ark. 

I  Clay 

53.3 

23.29 

9.52 

.36 

1.49 

5.16 

In  the  selection  of  raw  materials  the  aim  of  the  manu- 
facturers is  to  produce  a  raw  mixture  which  runs  approx- 
imately 70  to  75  per  cent  lime  carbonate  and  the  balance 
clay  (U.  S.  Geol.  Surv.,  21st  Ann.  Kept.,  VI :  404,  1900). 
The  proportions  of  clay  and  lime  rock  used  at  each  factory 
are  not  always  disclosed,  and  the  mixture  of  the  two  in- 


116 


ECONOMIC  GEOLOGY  OF  THE  UNITED  STATES 


gredients  is  kept  under  careful  control  by  frequent  chemical 
analysis,  since  slight  variations  from  the  proper  composi- 
tion may  injure  the  cement.  The  following  analyses  will 
serve  to  illustrate  the  composition  of  some  American  Port- 
land cements:  — 

ANALYSES  OF  CEMENTS 


SiO2 

A1208 

Fe203 

CaO 

MgO 

S08 

Empire  brand     .     . 

22.04 

6.45 

3.41 

60.92 

3.53 

2.73 

San  dusky  .... 

23.08 

6.16 

2.90 

62.38 

1.21 

1.66 

Alpha    

22.62 

8.76 

2.66 

61.46 

2.92 

1.53 

Distribution  of  Lime  and  Cement  Materials  in  the  United 
States.  Limestone  for  Lime.  —  Limestones  of  suitable  com- 
position for  burning  lime  are  so  widely  distributed  that  no 
particular  regions  or  states  require  special  mention.1  In  the 
New  England  states,  crystalline  limestones  are  the  chief 
source  of  supply.  In  the  Appalachian  states,  from  New 
York  to  Alabama,  there  are  many  Paleozoic  limestones  of 
high  purity,  notably  the  Trenton,  Lower  Helderberg,  and 
Carboniferous  limestones  (see  state  references).  The  same 
series  of  rocks  are  also  of  importance  in  the  Mississippi 
Valley  states  from  Tennessee  to  Michigan  (27).  Lime  of 
excellent  quality  is  obtained  from  the  Subcarboniferous  in 
Iowa  (41),  Kansas  (21),  and  Missouri  (41),  and  from  the 
Cretaceous  in  Texas  (41).  Limestones  suitable  for  lime 
manufacture  are  also  found  in  numerous  localities  in  the 
Pacific  coast  states  (41). 


1  Analyses  and  detailed  descriptions  will  be  found  in  the  areal  reports, 
mentioned  in  the  list  of  References. 


PLATE  X 


FIG.  1.  —Quarry  of  natural  cement  rock,  Cumberland,  Md.    Photo,  by  H.  Ries. 


FIG.  2.  — Marl  pit  at  Warners,  N.Y.     The  dark  streaks  are  peat,  and  the  marl  is 
underlain  by  clay.    Photo,  by  H.  Hies. 


LIME   AND   CALCAKEOUS   CEMENTS  117 

Hydraulic  Limes.  —  Largely  because  of  the  great  abun- 
dance of  natural  rock  cements,  which  are  of  superior  value, 
these  materials,  though  much  used  abroad,  are  of  no  im- 
portance in  the  United  States. 

Natural  Rock  Cements  (1,  41).  —  Calcareous  rocks  of  this 
class  are  found  at  a  number  of  points,  mainly  in  the  Paleozoic 
formations.  In  1903  they  were  worked  in  sixteen  different 
states,  eleven  of  which  are  east  of  the  Mississippi.  These 
are  found  at  a  number  of  points  in  the  Appalachian  region, 
but,  owing  to  the  folded  character  of  the  beds  (PL  X,  Fig. 
1),  their  extraction  is  often  difficult.  The  most  important 
natural  rock  cement  region  of  the  United  States  is  that  of 
Rosendale,  New  York  (32,  35),  where  the  cement  rocks  are 
found  in  the  Water  Lime  beds  at  the  top  of  the  Upper 
Silurian,  being  obtained  from  underground  workings.  The 
three  beds  are  interstratified  with  other  limestones,  and 
often  dipping  at  a  high  angle.  Their  thickness  ranges  from 
7  to  25  feet.  The  great  development  of  this  region  is  due 
partly  to  the  large  supply  of  raw  material,  and  partly  to  the 
proximity  to  New  York  City  and  the  possibility  of  shipment 
by  tide-water. 

Farther  west,  around  Akron,  New  York,  and  Buffalo  (31), 
the  cement  rock  occurs  at  a  somewhat  lower  horizon.  In 
eastern  Pennsylvania,  especially  in  the  vicinity  of  Coplay 
and  Catasauqua  (39),  cement  rock  of  Trenton  age  occurs  in 
a  region  of  marked  folding.  This  region,  though  an  im- 
portant producer  of  cement  rock,  is  even  more  important  as 
a  producer  of  Portland  cement  (41). 

The  Water  Lime  beds  again  form  an  important  source  of 
cement  rock  in  the  vicinity  of  Cumberland,  Maryland  (24) 
(PL  X,  Fig.  1),  where  there  are  four  beds  of  economic 


118          ECONOMIC   GEOLOGY   OF   THE  UNITED   STATES 

value,  ranging  from  6  to  17  feet  in  thickness,  and  separated 
by  calcareous  shales.  The  entire  series  is  highly  folded,  the 
dip  sometimes  being  as  much  as  90°. 

Cement  rock  is  also  obtained  in  southeastern  Ohio  (36); 
at  Louisville,  Kentucky  (23),  probably  the  second  most  im- 
portant center  in  the  United  States ;  in  the  Hamilton  rocks 
at  Milwaukee,  Wisconsin  (44) ;  and  at  Utica  and  La  Salle, 
Illinois  (17),  where  it  is  found  in  the  Calciferous  formation 
in  a  bed  from  6  to  8  feet  thick. 

Portland  Cements.  —  Clay  and  limestone,  in  one  form  or 
another,  are  so  widely  distributed  throughout  the  United 
States,  that  it  is  possible  to  manufacture  Portland  cement 
at  many  localities,  and  the  geologic  age  of  the  materials 
used  ranges  from  Ordovician  to  Pleistocene  (41).  Nine- 
teen states  were  making  this  cement  in  1903,  the  factories 
being  spread  over  the  country  from  the  Atlantic  to  the 
Pacific  (41). 

By  far  the  most  important  district  is  the  Lehigh  Valley 
in  Pennsylvania,  which  supplies  about  70  per  cent  of  the 
domestic  product.  Here  the  raw  materials  consist  of  beds 
of  argillaceous  limestone  and  nearly  pure  limestone,  this 
being  one  of  the  few  localities  where  such  a  mixture  is 
obtainable.  The  same  beds  are  found  in  the  adjacent  terri- 
tory of  New  Jersey  (30). 

In  the  eastern  half  of  New  York  (35)  the  Ordovician  and 
Silurian  limestones  form  an  inexhaustible  supply  of  material 
to  mix  with  Pleistocene  surface  clays.  In  the  south  central 
part  of  New  York  the  Tully  limestone  and  Hamilton  shales 
are  employed,  while  in  the  central  and  southwestern  portion, 
beds  of  marl  (PI.  X,  Fig.  2),  associated  with  surface  clays, 
are  utilized. 


LIME   AND   CALCAREOUS   CEMENTS  119 

Ohio  (36,  41),  Indiana  (18),  and  Michigan  (26,  28)  are 
important  Portland  cement  producing  states.  The  abun- 
dance of  marl  and  Pleistocene  clays  makes  them  the  favorite 
materials,  notwithstanding  the  fact  that  beds  of  Paleozoic 
limestones  occur  in  each  of  the  states.  Marl,  although  espe- 
cially abundant  in  Michigan,  is  found  in  many  states  lying 
east  of  the  Mississippi  and  north  of  the  terminal  moraine. 
It  is  precipitated  from  the  waters  of  ponds  through  the 
agency  of  minute  plants,  especially  CTiara  (26). 

In  Kansas  Carboniferous  shales  and  limestones  are  used 
for  making  Portland  cement  (21,  22),  and  in  Texas  and 
Arkansas  the  Cretaceous  shales  and  chalky  limestones  are 
employed  (13, 14) ;  Alabama  has  a  Cretaceous  limestone  of 
such  composition  that  very  little  clay  or  shale  has  to  be 
added  to  it  (12).  Portland  cement  is  also  manufactured  in 
North  Dakota  (41),  South  Dakota  (41),  Utah  (41),  Colorado 
(41),  and  California  (15). 

Uses  of  Lime.  —  The  most  important  single  use  of  lime 
is  for  mixing  with  sand  to  form  mortar,  and  many  thousands 
of  tons  are  used  annually  for  this  purpose.  In  addition 
to  this  use,  lime  is  employed  for  a  great  variety  of  pur- 
poses, of  which  the  following  are  the  most  important :  as 
a  purifier  in  basic  steel  manufacture;  in  the  manufacture 
of  refractory  bricks,  ammonium  sulphate,  soap,  bone  ash, 
gas,  potassium-dichromate,  paper,  pottery  glazes,  and  cal- 
cium carbide;  as  a  disinfectant;  as  a  fertilizer;  as  a  polish- 
ing material ;  for  dehydrating  alcohol,  preserving  eggs,  and 
in  tanning. 

Uses  of  Cement.  —  The  use  of  hydraulic  cement  is  con- 
stantly increasing  in  the  United  States,  this  being  specially 


120 


ECONOMIC   GEOLOGY   OF   THE  UNITED   STATES 


true  of  Portland  cement,  which  is  superseding  natural 
cement  to  a  great  extent,  and  is  finding  an  increasing  use 
in  building  and  engineering  operations.  For  pavements, 
Portland  cement  is  probably  more  extensively  used  in 
America  than  in  any  other  country;  and  as  an  ingredient 
of  concrete  it  is  widely  employed.  Blocks  weighing  as  much 
as  65  to  70  tons  have  been  made  for  harbor  improvements 
at  New  York  City  (37 a). 


Production  of  Cement.  —  The  following  tables  give  the 
production  of  natural-rock  and  Portland  cement.  Those 
given  for  the  latter  cover  a  greater  period  than  those  of  the 
former,  and  are  grouped  with  figures  of  import  and  consump- 
tion in  order  to  show  more  clearly  the  tremendous  growth 
of  the  American  Portland  cement  industry. 


PRODUCTION  OF  NATURAL  CEMENT  IN  UNITED  STATES 


1901 

1902 

1903 

QUANTITY 

VALUE 

QUANTITY 

VALUE 

QUANTITY 

VALUE 

barrels 

barrels 

barrels 

New  York  . 

2,234,131 

$1,117,066 

3,577,340 

$2,135,036 

2,417,137 

$1,510,529 

Pennsylvania  . 

942,364 

376,954 

796,876 

340,669 

1,339,090 

576,269 

Kentucky/ 

2,150,000 

752,500 

1,727,146 

869,163 

533,573 

766,786 

Wisconsin   .     . 

481,020 

182,788 

437,913 

162,628 

330,522 

139,373 

Illinois    .    .    . 

469,842 

187,936 

607,820 

156,855 

543,132 

178,900 

Maryland    .    . 

351,329 

175,665 

409,200 

150,680 

269,957 

138,619 

Others     .     .    . 

456,137 

263,369 

488,010 

261,599 

569,860 

365,044 

Total     .    . 

7,084,823 

$3,056,278 

8,044,305 

$4,076,630 

7,030,271 

$3,675,520 

LIME   AND    CALCAREOUS   CEMENTS  121 

PRODUCTION  OF  PORTLAND  CEMENT  IN  UNITED  STATES 


1891 

1900 

1901 

1902 

1903 

Production  of  United  States 
Imports     

barrels 
454,813 
2,988,313 

barrels 
8,482,020 
2,386,683 

barrels 
12,711,225 
922,426 

barrels 
17,230,644 
1,961,013 

barrels 
22,342,973 
2,251,969 

Total  

3,443,126 

10,868,703 

13,633,651 

19,191,657 

24,594,942 

Exports  (domestic  and  for- 
eign)       

- 

139,939 

417,625 

373,414 

285,463 

Total  consumption  .    . 
Percentage     of     domestic 
production  to  total  con- 
sumption in  United  States 

3,443,126 
13.2 

10,728,764 
79.1 

13,216,026 
96.2 

18,818,248 
91.6 

24,309,479 
91.9 

PRODUCTION  OF  PORTLAND  CEMENT  BY  STATES  IN  1903 


BARRELS 

VALUE 

9,754,313 

$11  205  899 

2  693  381 

2  944  604 

1  955  183 

2  674  780 

Illinois 

1  957  500 

1  914  500 

Indiana    

1,077,137 

1  347  797 

1  019  68? 

1  285  310 

Ohio     

729,519 

998  300 

All  others 

3  856  °58 

5  34°  136 

Total 

22  349  973 

$°7  713  319 

REFERENCES  ON  LIME  AND  CEMENT  MATERIALS 

TECHNOLOGY.  1.  Cummings,  American  Cements,  Boston,  1898.  (Many 
analyses.)  2.  Eckel,  Min.  Indus.  X :  84,  1902.  (Slag  cement  manu- 
facture.) 3.  Eckel,  Amer.  Geol.  XXIX:  146,  1902.  (Classifica- 
tion.) 4.  Green,  Portland  Cement  Industry  of  the  World,  Journal 
of  Association  of  Civil  Engineering,  XX:  391,  1898.  5.  Gilmore, 
Practical  Treatise  on  Limes,  Hydraulic  Cements  and  Mortars,  N.  Y., 
D.  Van  Nostrand,  1872.  6.  Jameson,  Portland  Cement;  its  Manu- 
facture and  Use,  New  York,  1898.  7.  Lewis,  Manufacture  of 


122    ECONOMIC  GEOLOGY  OF  THE  UNITED  STATES 

Hydraulic  Cement  in  United  States,  Mineral  Industry,  VI :  91,  1898. 
8.  Richardson,  Series  of  Articles  on  Lime  and  Cement  Mortars 
in  the  Brickbuilder,  1897  and  1898.  9.  Schoch,  Die  Moderne 
Aufbereitung  u.  Wertung  der  Mortel-Materialien,  Berlin,  1896. 
10.  Spalding,  Hydraulic  Cement;  its  Properties,  Testing,  and  Use, 
New  York,  1897,  John  Wiley  &  Sons. 

LOCALITY  REPORTS.  Alabama:  11.  Meissner,  Ala.  Ind.  and  Sci., 
Proc.,  IV:  12.  (Birmingham  district  limestone.)  12.  Smith,  Ala. 
Geol.  Surv.,  Bull.  8,  1904.  (Many  analyses.) — Arkansas:  13.  Bran- 
ner,  Amer.  Inst.  Min.  Engrs.,  Trans.  XXVII :  42,  1898.  (S.  W. 
Ark.)  14.  Taff,  U.  S.  Geol.  Surv.,  22d  Ann.  Rept.,  111:687,  1902. 
(S.  W.  Ark.)  —  California :  15.  Grimsley,  Eng.  and  Min.  Jour., 
LXXII:  71,  1901.  (Cement  industry.)  16.  Irelan,  8th  Ann.  Rept. 
State  Mineralogist :  865  to  883,  1888 ;  also  9th  Ann.  Rept. : 
309-311,  1889;  13th  Ann.  Rept.  Calif.  State  Mineralogist:  627, 
1896  ;  12th  Ann.  Rept. :  391,  1894.  (Cements.)  —  Illinois  :  17.  Free- 
man, Amer.  Inst.  Min.  Eng.,  Trans.  XIII:  172,  1885.  (La  Salle, 
natural  rock  cement.)  —  Indiana:  18.  Blatchley,  25th  Ann.  Rept. 
Ind.  Dept.  Geol.  and  Nat.  Res.,  1900 :  323,  1901.  (Bedford  lime- 
stone.) 19.  Siebenthal,  25th  Ann.  Rept.  Ind.  Dept.  Geol.  and 
Nat.  Hist.  1900 :  331,  1901.  (Silver  Creek  hydraulic  limestone.)  — 
Iowa :  20.  Houser,  la.  Geol.  Surv.,  1 :  199,  1893.  (Niagara  lime- 
stone.) —  Kansas :  21.  Haworth,  Kas.  Geol.  Surv.,  Ill:  31,  1898. 
22.  Haworth  and  Schrader,  U.  S.  Geol.  Surv.,  Bull.  260 :  506,  1905. 
(Independence  Quadrangle.)  —  Kentucky :  23.  Kentucky  Geol.  Surv., 
New  Series,  IV :  404.  —  Maryland :  24.  Clark  and  others,  Md.  Geol. 
Surv.  Rept.  on  Allegheny  Co.:  185,  1900.  (Lime  and  cements.) 
25.  Martin,  Md.  Geol.  Surv.  Rept.  on  Garrett  Co. :  220,  1902.  — 
Michigan :  26.  Hale  and  others,  Mich.  Geol.  Surv.,  VHI,  Pt.  3,  1903. 
(Marl  for  Portland  cement.)  27.  Lane,  Eng.  and  Min.  Jour.,  LXXI : 
662, 693,  and  725,  1901.  (Mich,  limestones.)  28.  Russell,  U.  S.  Geol. 
Surv.,  22d  Ann.  Rept.,  Ill:  629,  1902.  (Mich.  Portland  cement 
industry.)  — Mississippi:  29.  Crider,  U.  S.  Geol.  Surv.,  Bull.  260: 
510,  1905.  (N.  E.  Miss.)  — New  Jersey:  30.  Kiimmel,  Ann.  Rept. 
N.  J.  State  Geologist,  1900 :  9.  (N.  J.  Portland  cement  industry.)  — 
New  York :  31.  Bishop,  15th  Ann.  Rept.  N.  Y.  State  Geologist :  338, 
1897.  (Erie  Co.)  32.  Nason,  Rept.  of  N.  Y.  State  Geologist,  1893  : 
375.  (Ulster  Co.)  33.  Pohlman,  Amer.  Inst.  Min.  Eng.,  Trans. 
XVIII :  250, 1889.  (Cement  rock  at  Buffalo.)  34.  Ries,  U.  S.  Geol. 
Surv.,  17th  Ann.  Rept.,  Ill  (cont.)  :  795, 1896.  (Limestone  quarries, 
New  England  and  New  York.)  35.  Ries  and  Eckel,  Bull.  N.  Y. 
State  Museum,  44, 1901.  (N.  Y.  lime  and  cement  industry.)  —  Ohio  : 
36.  Lord,  Ohio  Geol.  Surv.,  VI :  671,  1888.  (Natural  and  artificial 


LIME  AND  CALCAREOUS   CEMENTS  123 

cements.)  37.  Orton,  Ohio  Geol.  Surv.,  VI :  703,  1888.  (Lime.) 
37 a.  Eno,  Ohio  Geol.  Surv.,  4th  Series,  Bull.  2,  1904.  (Uses  of 
cement.)  376.  Bleininger,  Ibid.,  Bull.  3.  (Manufacture  of  cement.) 
—  Pennsylvania :  38.  Prime,  Second  Geol.  Surv.  of  Pa.,  Rep.  DD :  59, 
1878.  39.  Eckel,  U.  S.  Geol.  Surv.,  Bull.  225 :  448,  1904.  (Lehigh 
district.)  40.  Clapp,  U.  S.  Geol.  Surv.,  Bull.  249, 1905.  (Limestones, 
S.  W.  Pa.)  —  United  States  :  41.  Eckel,  U.  S.  Geol.  Surv.,  Bull.  260  : 
497, 1905.  Also  Bull.  243.  (Cement  resources  and  industry.) — Vir- 
ginia: 42.  Catlett,  U.  S.  Geol.  Surv.,  Bull.  225 :  457,  1904.  (Cement 
resources,  Valley  of  Va.)  43.  Also  Bassler,  Ibid.,  Bull.  260:  531, 
1905.  — Wisconsin:  44.  Chamberlin,  Geol.  of  Wis.,  II,  Pt.  2:  395, 
1873.  (Natural  rock  cement.) 


CHAPTER  VI 


SALINES 

Salt.  —  Common  salt,  the  chloride  of  sodium  (NaCl),  is 
a  widely  distributed  mineral,  being  found,  (1)  in  solution 
in  sea  water  or  salt  lakes;  (2)  as  solid  masses  termed  rock 
salt ;  (3)  as  natural  brine  in  cavities  or  pores  of  the  rocks, 
from  which  it  may  exude  as  salt  springs  or  be  tapped  by 
wells ;  and  (4)  in  marshes  and  soils. 

Although  all  four  of  these  methods  of  occurrence  may 
serve  as  commercial  sources  of  salt,  it  is  only  the  second 
that  is  of  great  economic  importance. 

Occurrences  of  Salt  in  Sea  and  Lake  Waters.  —  Salt  is 
present  in  all  ocean  water,  and  also  in  that  of  most  inland 
lakes  or  seas  having  no  outlet.  As  can  be  seen  from  the 
following  analyses,  the  percentage  of  salt  is  greater  in  some 
salt  lakes  than  in  the  ocean :  — 


PEBCENTAGE  OF  SALTS  IN  SOLID  MATTER 

£  o 

LOCALITY 

S  & 

1 

Jl 

£ 

s 

0 

€ 

&  M 

a  tt> 

o 

o 

•6 

ft 

f, 

M 

S 

*% 

5 

M 

»a 

Black  Sea  .... 

1.77 

98.23 

79.39 

1.07 

7.38 

.03 

.60 

8.32 

3.21 

Mediterranean  Sea  . 

3.37 

96.63 

77.03 

2.48 

8.76 

.49 

2.76 

8.34 

.10 

Atlantic  Ocean    .    . 

3.63 

96.37 

77.07 

3.89 

7.86 

1.30 

4.63 

5.29 

— 

CaClj 

Dead  Sea    .... 

22.30 

77.70 

36.55 

4.57 

45.20 

.85 

.45 

— 

11.38 

K2S04 

Great  Salt  Lake  .    . 

14.99 

85.01 

79.12 

.57 

9.93 

— 

.56 

6.21 

3.47 

124 


SALINES  125 

Salt  is  sometimes  obtained  by  artificial  evaporation  from 
both  the  ocean  and  salt  lakes ;  but  in  the  United  States  this 
plan  is  profitable  only  under  exceptional  conditions,  as  around 
San  Francisco  Bay,  California  (6),  or  Great  Salt  Lake,  Utah. 

Rock  Salt.  —  Rock  salt,  which  is  the  most  important  source 
of  commercial  salt,  is  present  in  layers  of  variable  thickness 
and  purity  embedded  with  sedimentary  rocks,  such  as  shales 
or  sandstones.  It  is  frequently  associated  with  gypsum,  and 
less  commonly  with  limestone,  or  easily  soluble  compounds 
of  magnesia,  potash,  and  lime.  The  salt  beds  vary  in  thick- 
ness from  a  few  inches  up  to  as  much  as  3600  feet  (Speren- 
berg,  Germany),  and  while  found  in  all  geological  formations 
from  the  Cambrian  to  the  Pleistocene,  except  the  Creta- 
ceous, the  rock  salt  of  the  United  States  is  not  found  in 
formations  older  than  the  Upper  Silurian. 

Origin  of  Rock  Salt  (5).  —  One  of  the  interesting  problems 
of  geology  has  been  to  find  a  correct  theory  to  account  for 
salt  deposits  of  enormous  thickness  and  often  high  purity. 
It  is  well  known  that  salt  is  deposited  in  the  course  of 
evaporation  of  inland  seas,  such  as  the  Dead  Sea,  and  this 
is  perhaps  the  origin  of  some  of  the  salt  beds  found  in  the 
strata.  But  in  many  cases  the  material  was  evidently  de- 
posited in  close  connection  with  the  open  ocean,  being  both 
overlain  and  underlain  by  massive  sediments  with  which 
it  is  directly  continuous.  It  is  inconceivable  that  such 
beds  were  precipitated  in  the  open  ocean,  though  they  may 
well  have  been  formed  in  seas  or  bays  more  or  less  com- 
pletely cut  off  from  the  ocean. 

This  explanation,  elaborated  by  Ochseuius  (4),  assumes 
a  barrier  partly  shutting  out  the  ocean  water.  Evaporation 


126          ECONOMIC   GEOLOGY   OF  THE  UNITED   STATES  ^ 

on  the  inclosed  area  of  the  sea  exceeds  the  supply  of  water 
from  inflowing  rivers  and  from  the  open  ocean.  Therefore 
the  water  on  the  surface  of  the  sea  becomes  more  dense  and 
settles  to  the  bottom  of  the  basin,  being  prevented  from 
escape  into  the  open  ocean  by  the  barriers  at  the  entrance. 
As  the  surface  of  the  bay  is  lowered  by  evaporation,  ocean 
water  enters,  furnishing  a  constant  supply  of  salt.  If  the 
barrier  is  complete,  forming  a  bar,  sea  water  may  enter  only 
at  times  of  high  tide  or  storm.  Eventually  evaporation  will 
so  concentrate  the  solution  in  the  bay  as  to  cause  the  pre- 
cipitation of  sodium  chloride  and  other  salts.  So  long  as 
these  conditions  lasted,  salt  would  be  precipitated,  but  beds 
of  clayey  material  would  be  deposited  wherever  fine-grained 
sediment  was  supplied  from  the  land. 

As  will  be  seen  by  reference  to  the  sea-water  analyses 
given  above,  there  are  other  salts  present  besides  sodium 
chloride,  and  these  will  separate  out  in  order  of  their 
solubilities,  the  least  soluble  ones  being  precipitated  first. 
The  order  of  precipitation  would  therefore  be :  (1)  small 
amounts  of  lime  carbonate  and  some  hydrous  iron  oxide ; 
(2)  most  of  the  sulphate  of  lime  present ;  (3)  a  mixture  of 
sodium  chloride  and  lime  sulphate ;  (4)  sodium  chloride  of 
high  purity ;  (5)  a  mixture  of  sodium  chloride  and  soluble 
salts  of  magnesia,  potash,  bromine,  and  iodine. 

This  accounts  for  the  frequent  association  of  gypsum  with 
salt ;  but  the  potash  and  magnesia  salts,  precipitated  last,  are 
rare,  because  even  after  being  precipitated  they  may,  owing 
to  their  easy  solubility,  be  removed  by  an  influx  of  fresh 
water  or  by  leaching  of  the  deposit.  The  only  locality 
where  the  complete  series  is  found  is  at  Stassfurt, 
Prussia. 


SALINES  127 

This  deposit,  which  is  of  Permian  age,  is  one  of  the  most  interesting 
in  the  world.  It  shows  the  following  section :  at  the  bottom  is  the 
main  bed  of  rock  salt  which  is  broken  up  into  layers  2  to  5  inches  thick 
by  layers  of  anhydrite.  Above  this  comes  200  feet  of  rock  salt,  with 
which  are  mixed  layers  of  magnesium  chloride  and  polyhalite  (K2SO4, 
MgSO4,  2  CaSO4,  2  H2O).  Resting  on  this  is  180  feet  of  rock  salt,  with 
alternating  layers  of  sulphates,  chiefly  kieserite,  the  sulphate  of  magnesia. 
These  layers  are  about  1  foot  thick.  Lastly,  and  uppermost,  is  a  135- 
foot  bed  consisting  of  a  series  of  reddish  layers  of  rock  salt  and  salts  of 
magnesia  and  potassium,  kainite  (K2SO4,  MgSO4,  MgCl2,  6  H2O),  kieserite 
(MgSO4),  carnallite  (KC1,  MgCl2,  6H2O),  tachhydrite  (CaCl2,  2MgCl2, 
12H2O),  as  well  as  masses  of  snow-white  boracite  (Mg7Cl2B16O30). 

Natural  Brines.  —  These,  sometimes  found  in  porous  layers 
of  the  rocks,  may  result  either  from  sea  water  imprisoned 
in  the  layers  of  sediment  or  from  the  solution  of  rock  salt 
by  percolating  waters. 

Salt  Marshes  and  Soils.  —  When  away  from  the  ocean, 
these  owe  their  salinity  to  the  infiltration  of  brine  from 
neighboring  saliferous  formations.  They  sometimes  repre- 
sent the  site  of  former  salt  lakes. 

Distribution  of  Salt  in  the  United  States  (Fig.  26).  —  In 
1903  most  of  the  domestic  production  came  from  nine  states, 
either  in  the  form  of  artificial  brine  obtained  by  forcing 
water  through  wells  to  the  salt,  which  is  then  brought  up 
in  solution,  or  else  as  rock  salt,  raised  through  shafts  from 
underground  workings. 

New  York  (13).  — Salt  was  manufactured  from  brine  springs 
at  Onondaga  Lake  as  early  as  in  1788 ;  but  the  presence  of 
rock-salt  beds  was  not  suspected  until  1878,  when  a  bed 
seventy  feet  thick  was  struck  in  drilling  for  petroleum  in 


128 


ECONOMIC    GEOLOGY   OF   THE   UNITED   STATES 


Wyoming  County.  Since  then  the  development  of  the  salt 
industry  has  been  so  rapid  that  for  some  years  New  York 
has  been  one  of  the  two  leading  salt-producing  states. 

The  salt  occurs  in  lenticular  masses  interbedded  with 
soft  shales  of  the  Salina  series,  which  also  carry  gypsum 
deposits.  The  outcrop  of  the  formation  coincides  approxi- 


FIG.  26. —  Map  showing  known  occurrences  of  salt  in  United  States,  compiled 
from  various  geological  survey  reports. 

mately  with  the  line  of  the  New  York  Central  Railroad, 
but  owing  to  its  soluble  character,  no  salt  is  found  along 
the  outcrops.  The  beds  dip  southward  from  25  to  40 
feet  per  mile,  so  that  the  depth  of  the  salt  beneath  the 
surface  increases  in  this  direction. 

At  Ithaca,  salt  is  struck  at  2244  feet,  and  there  are  seven  beds.  The 
thickness  of  the  individual  beds  varies,  but  the  greatest  known  thickness 
is  in  a  well  near  Tully,  where  325  feet  of  solid  salt  was  bored  through. 
Though  most  of  the  New  York  product  is  obtained  from  artificial  brines, 
a  small  quantity  is  mined  by  shafts. 


PLATE  XI 


FIG.  1.  —  Interior  view  of  salt  mine,  Livonia,  N.Y.    Both  roof  and  pillars  are  rock 

salt. 


FIG.  2.  —  Borax  mine  near  Daggett,  Calif.    Photo,  loaned  by  G.  P.  Merrill. 


SALINES  129 

Michigan  (11). — Salt  in  Michigan  is  obtained  both  from 
natural  brines  and  from  brines  obtained  by  dissolving  rock 
salt,  as  in  New  York.  The  natural  brines  occur  in  the 
sandstones  of  the  Subcarboniferous,  the  most  important 
locality  being  in  the  Saginaw  Valley,  where  the  brines  are 
found  in  the  Napoleon  or  Upper  Marshall  sandstone.  They 
are  remarkable  for  the  large  amount  of  bromine  contained, 
more  than  half  the  bromine  produced  in  the  United  States 
being  obtained  here.  The  vast  beds  of  rock  salt  which 
occur  in  the  Salina  (Monroe)  are  exploited  along  the  Detroit 
and  St.  Clair  rivers  and  at  Manistee  and  Ludington.  The 
salt  is  dissolved  by  lake  water  pumped  down  and  then  re- 
evaporated,  and  soda  ash  (sodium  carbonate)  is  made  from 
the  salt  to  a  very  great  extent,  by  forced  reaction  with 
calcium  carbonate.1 

Other  Eastern  States.  —  In  the  Holston  Valley  of  south- 
western Virginia  salt  is  obtained  by  wells  from  the  Lower 
Carboniferous  shaly  limestones.  Part  of  the  product  is 
marketed  as  salt,  and  the  balance  is  used  in  the  manufacture 
of  alkali  (19). 

Brine  is  obtained  from  the  Salina  and  Salt  sand  of  Ohio 
(14),  and  from  those  portions  of  Pennsylvania  and  West 
Virginia  adjacent  to  the  Ohio  salt  district.  In  the  Kanawha 
Valley  of  West  Virginia  a  natural  brine  is  obtained  by  wells 
from  the  oil  horizons.  Brines  are  also  present  in  the  Car- 
boniferous of  Illinois. 

Louisiana  (8-10) .  —  Brine  occurs  in  springs  and  wells  in 
the  Cretaceous  area  of  northern  Louisiana,  but  the  most 
important  source  of  salt  is  in  the  extensive  beds  of  rock  salt 

1  Private  communications  from  Dr.  A.  C.  Lane,  State  Geologist  of 
Michigan. 


130          ECONOMIC   GEOLOGY  OF   THE   UNITED  STATES 

found  in  the  southern  portion  of  the  state.  These  occur  in 
a  series  of  low  knolls,  called  the  Five  Islands,  beneath  a 
series  of  clay,  sand,  and  gravel  beds.  Though  structural 
details  are  lacking,  there  seems  in  one  case  to  be  a  dome 
fold  and  in  Petite  Anse  a  block  fault.  The  age  of  the  salt 
beds  is  Prepleistocene.  Although  the  amount  of  rock  salt 
present  is  evidently  great,  borings  in  one  case  having  re- 
vealed a  thickness  of  1756  feet  of  solid  salt,  these  deposits 
yield  but  a  small  percentage  of  the  country's  output. 

Kansas  (7). —  Salt  is  found  in  this  state  under  the  follow- 
ing conditions:  (1)  in  the  northern  and  central  parts  of  Kansas 
as  brine  in  salt  marshes  derived  by  leaching  from  the  salifer- 
ous  Dakota  shales ;  (2)  a  limited  amount  in  eastern  Kansas 
from  wells  sunk  in  the  Carboniferous ;  (3)  in  the  Permian 
of  south  central  Kansas  as  beds  of  rock  salt.  At  the  present 
time  the  rock  salt  is  the  most  important  commercial  source, 
being  obtained  in  part  as  artificial  brines  and  in  part  as 
rock  salt.  The  thickness  of  the  salt  varies,  the  greatest 
aggregate  thickness  recorded  in  any  well  being  324  feet. 
The  deposits  thin  out  to  the  eastward,  and  the  north  and 
south  limits  are  fairly  well  known,  but  the  western  boundary 
remains  undefined.  The  absence  of  gypsum  in  close  asso- 
ciation with  the  salt  is  a  significant  fact,  but  farther  south 
it  is  found  at  a  lower  horizon,  and  the  separation  of  the  two 
is  explained  by  a  shifting  sea  bottom  during  deposition. 

Other  Western  States  (16,  17).  — Rock  salt  has  been  found 
at  several  localities  in  Texas,  notably  in  Mitchell  County 
and  under  the  oil  beds  at  Beaumont ;  but  none  is  yet  pro- 
duced. In  Utah,  some  salt  is  obtained  by  evaporating  the 
waters  of  Great  Salt  Lake  (18).  In  California  the  main 
supply  of  salt  is  obtained  by  evaporating  sea  water  (6),  an 


SALINES 


131 


elaborate  system  of  ponds,  covering  thousands  of  acres, 
having  been  built  on  San  Francisco  Bay.  These  are  filled 
at  high  tide,  and  the  salt  obtained  by  natural  evaporation. 
A  remarkable  deposit  of  salt  is  worked  at  Salton  Lake. 
This  is  a  depression  27  miles  long,  3^  to  9  miles  wide,  and 
at  its  lowest  point  280  feet  below  sea  level.  The  deposit 
is  formed  by  evaporation  of  the  lake  waters,  which  are  fed 
by  saline  springs  from  the  surrounding  foothills.  The  salt, 
which  has  accumulated  to  a  depth  of  6  inches,  is  gathered  by 
scrapers.  Salt  is  also  found  in  marshes,  springs,  or  wells  in 
a  number  of  other  localities  in  California  (6). 

ANALYSES  OF  ROCK  SALT  FROM  VARIOUS  LOCALITIES 


s§ 

R§ 

Ei 

1$ 

l! 

•<" 

2  j 

* 

S3 

a  a 

o  * 

3  3 

9\  * 

3  3  *• 

\ 

£o 

o  o 

So 

O  n 

S£ 

<££ 

* 

Retsof.  N.Y.  .     .     . 

98.701 

Tr. 

_ 

.446 

— 

.743 

Tr 

F.  E.  Englehardt 

Pearl  Creek,  N.Y. 

96.885 

.157 

.103 

.437 

— 

1.21 

1.21 

F.  E.  Englehardt 

Petite  Anse,  La.     . 

98.90 

.146 

.022 

.838 

— 

.014 

.08 

P.  Collier 

Saltville,  Va.      .    . 

99.084 

Tr. 

— 

.446 

— 

.47 

— 

C.  B.  Hayden 

ANALYSES  OF  SOLID  MATTER  OF  BRINES  FROM  VARIOUS  LOCALITIES 


„ 

*  - 

a 
2  a 

a  5 

h 

^ 

3  K 

b 
O 

LOCALITY 

y-  3 
to  23 

H    S 

S5     3 

3  s 

-  ^ 

"*  -^ 

Sic 

—     **     E 

ATTTHOBITY 

z  s 

3  3 

§  3 

s  a 

9  j 

ui  —  5 

|  n  £ 

§     -^     « 

00 

ii 

a* 

4li 

B  O   ffi 

Warsaw,  N.Y. 

97.60 

.51 

.20 

1.68 

_ 

_ 

26.34 

1.204 

Englehardt 

Syracuse,  N.Y. 

95.966 

.90 

.69 

2.54 

— 

.004 

18.50 

1.142  IG.  H.  Cook 

Saginaw,  Mich. 

82.14 

12.39 

5.01 

.46 

— 

— 

21.32 

—    Ic.A.Goessman 

Bay  City,  Mich. 

91.95 

3.19 

2.48 

2.39 

— 

— 

16.61 

— 

C.  A.  Goessman 

Kanawha.W.Va. 

79.45 

16.48 

4.07 

— 

— 

— 

9.20 

1.07H 

G.  H.  Cook 

Pittsburg,  Pa. 

81.27 

13.93 

4.80 

— 

.—  - 

— 

2.80 

1.019 

G.H.  Cook 

Saltville,  Va. 

97.792 

.033 

— 

2.17 

'"*• 

Tr. 

24.60 

— 

C.  B.  Hayden 

Extraction.  —  When  salt  forms  underground  deposits,  it 
has   to  be   extracted   either   by   a   process   of    solution   or 


132 


ECONOMIC   GEOLOGY   OF   THE   UNITED    STATES 


mining.  In  the  former  case  water  is  forced  down  to  the 
salt  bed  through  a  well,  for  the  purpose  of  dissolving  the 
salt,  the  brine  being  brought  to  the  surface  and  evaporated, 
sometimes  by  solar  heat,  but  more  commonly  by  artificial 
means.  In  the  latter  case  a  shaft  is  sunk  to  the  salt  bed, 
and  the  material  mined  like  coal  and  brought  to  the  sur- 
face in  lumps,  known  as  rock  salt.  Natural  brines  are 
pumped  to  the  surface  for  evaporation.  In  the  evapora- 
tion of  brine  care  has  to  be  taken  to  separate  the  gypsum 
and  other  soluble  impurities  present,  which  precipitate  be- 
fore the  salt  does. 

Uses.  —  Salt  is  largely  used  in  the  meat-packing  business 
and  the  manufacture  of  dairy  products,  as  well  as  for 
domestic  purposes.  Therefore  a  number  of  different  grades 
are  called  for,  known  under  various  names,  such  as  table, 
dairy,  common,  fine,  packers,  solar,  rock,  milling,  etc.  Large 
quantities  of  salt  are  also  consumed  in  the  manufacture  of 
soda  ash,  sodium  carbonate,  caustic  soda,  and  other  sodium 
salts.  The  chlorination  of  gold  ores  calls  for  an  additional 
large  amount. 

Production  of  Salt.  —  The  increase  in  the  amount  of  salt 
produced  has  been  very  marked,  but  it  has  been  accom- 
panied by  a  decrease  in  price,  as  shown  in  the  statistics 
given  below  : — 

PRODUCTION  OF  SALT  IN  UNITED  STATES  FROM  1880  TO  1900 


YEAR 

BARBELS 

VALUE 

YEAR 

BARRELS 

VALUE 

1880  .     .     . 
1885  .     .     . 
1890  .     .     . 

5,961,060 
7,038,653 
8,876,991 

$4,828,566 
4,825,345 
4,752,286 

1895     .     . 
1900     .    . 

13,699,649 
20,869,342 

$4,423,084 
6,944,603 

SALINES  183 

PRODUCTION  OF  SALT  BY  STATES  FROM  1901  TO  1903 


19 

01 

19 

02 

19 

03 

BARRELS 

TALUK 

BABBELS 

VALUE 

BABBELS 

VALUE 

New  York 

7,286,320 

$2,089,834 

8,523,389 

$1,938,539 

8,170,648 

$2,007,807 

Michigan 

7,729,641 

2,437,677 

8,131,781 

1,535,823 

4,2!  (7,542 

1,119,984 

Kansas  . 

2,087,791 

614,365 

2,158,486 

514,401 

1,555,934 

564,232 

Ohio  .     . 

1,153,535 

455,924 

2,109,987 

593,504 

2,798,888 

795,897 

California      . 

601,659 

133,656 

682,660 

253,085 

629,701 

198,630 

Texas    . 

(a) 

(a) 

347,906 

143,683 

314,000 

117,647 

West  Virginia 

231,722 

94,732 

208,592 

97,721 

244,236 

35,797 

Utah      . 

324,484 

326,016 

417,501 

270,626 

212,955 

181,710 

Louisiana 

(a) 

(a) 

(a) 

(a) 

568,93(5 

178,342 

Other  States  . 

1,141,509 

465,245 

1,268,929 

321,254 

175,238 

86,942 

Total  .    . 

20,566,661 

$6,617,449 

23,849,231 

$5,668,636 

18,968,089 

$5,286,988 

(a)  Included  in  "  Other  States." 

The  exports  in  1903  were  25,449,630  Ibs.,  valued  at 
§95,570  ;  while  the  imports  for  the  same  year  amounted  to 
331,961,807  Ibs.,  valued  at  $495,948. 

WORLD'S  PRODUCTION  OF  SALT  IN  1902 


COUNTRY 

SHORT  TONS 

VALUE 

United  States    
United  Kingdom  

3,339,891 
2,121,126 
982,479  (a) 
1,745,226 
761,575  (rf) 
505,401 
575,936 
1,913,696  (e) 
470,057 
1,165,291 
63,056 
125,467 

$5,668,636 
2,886,665 
2,605,800  (a) 
4,992,600 
4,459,245  (rf) 
711,400 
16,071,930 
2,767,168  (e) 
707,424 
1,554,914 
288,581 
970,522 

Japan  

Italy 

Russia  

Canada         

Others 

Total     

13,769,201 

$43,684,935 

(a)  Includes  Algeria. 

(d)  Production  and  value,  1901. 

(e)  Production  and  value,  1901. 


131          ECONOMIC   GEOLOGY   OF   THE  UNITED   STATES 

REFERENCES  OW  SALT 

TECHNOLOGY  AND  ORIGIN.  1.  Chatard,  U.  S.  Geol.  Surv.,  7th  Ann. 
Kept. :  491,  1888.  2.  Englehardt,  N.  Y.  State  Museum,  Bull.  No. 
XI :  38,  1893.  3.  Hubbard,  Mich.  Geol.  Surv.,  V,  Pt.  II :  1,  1895. 
4.  Ochsenius,  Chem.  Zeit.,  XI:  1887.  (Bar  theory.)  5.  Wilder, 
Jour.  Geol.,  XI :  725,  1903. 

AREAL.  California:  6.  Bailey,  Calif.  State  Min.  Bureau,  Bull.  XXIV: 
105,  1902.  —  Kansas:  7.  Kirk  and  Haworth,  Min.  Resources  of  Kas., 
1898:  67.  —  Louisiana:  8.  Lucas,  Amer.  Inst.  Min.  Engrs.,  Trans. 
XXIX  :  462,  1900.  (Rock  salt.)  9.  Veatch,  La.  Exp.  Sta.,  Pt.  V : 
209,  1899.  (Rock  salt.)  10.  Veatch,  ibid.,  Pt.  VI :  47,  1902.  (N. 
La.  salines.)  —  Michigan:  11.  Lane,  Mich.  Geol.  Surv.,  Ann.  Rept., 
1901 :  241,  1902.  — New  Mexico:  12.  Darton,  U.S.  Geol.  Surv.,  Bull. 
260:  565,  1905.  (Zuni.)  —  New  York:  13.  Merrill,  N.  Y.  State 
Museum,  Bull.  XI,  1893.  — Ohio:  14.  Root,  Ohio  Geol.,  VI:  653, 
1888.  —  Oklahoma  :  15.  Gould,  Kas.  Acad.  Soc.,  Trans.  XVII :  181, 
1901.  (Salt  plains.)  — Texas  :  16.  Cummins,  Tex.  Geol.  Surv.,  2d 
Ann.  Rept.:  444,  1890.  (Northwestern  Texas.)  17.  Richardson, 
U.  S.  Geol.  Surv.,  Bull.  260 :  572,  1905.  (Trans-Pecos  regions.)  — 
Utah  :  18.  U.  S.  Geol.  Surv.,  Min.  Res.,  1888:  605,  1890.  — Virginia: 
19.  Eckel,  U.  S.  Geol.  Surv.,  Bull.  213 :  407,  1903.  (S.  W.  Va.) 

BORAX 

Borax  Minerals  (3,4). — The  chief  minerals  containing 
boron  are  borax,  tincal,  or  sodium  biborate,  Na2B4O7, 
10  H2O  ;  colemanite,  Ca2B6On,  5  H2O  ;  ulexite,  CaNaB5O9, 
8  H2O  ;  boracite,  2  Mg3B8O15,  MgCl2.  These  minerals  are 
found  usually  as  incrustations  in  alkaline  marshes,  or  in 
lake  waters  of  arid  regions,  or  as  bedded  deposits.  In 
some  localities  boric  acid  is  found  in  fumarolic  vapors. 

Distribution  in  United  States  (5).  —  Deposits  of  borax 
have  up  to  the  present  time  been  discovered  only  in  Cali- 
fornia (1,  2),  Nevada,  and  Oregon.  Borax  was  originally 
obtained  by  evaporation  from  the  waters  of  Clear  Lake, 
north  of  San  Francisco,  being  produced  in  commercial 
quantities  in  1864,  and  the  solution  was  enriched  by  crys- 


SALINES  135 

talline  borax  obtained  from  the  marshes  surrounding  the 
lake.  This  and  other  lakes  of  California  were  worked 
until  the  discovery  of  large  deposits  of  nearly  pure  borax 
in  alkaline  marshes  of  eastern  California  and  western  Nevada 
in  the  early  seventies.  Several  refining  plants  were  located 
at  these  marshes,  and  the  product  was  sometimes  hauled  a 
hundred  miles  to  the  railroad.  Increased  production  and 
importation  from  Italy,  however,  reduced  the  price  and 
caused  these  plants  to  be  abandoned. 

The  discovery,  in  1890,  that  the  marsh  borax  was  a 
secondary  deposit,  derived  from  easily  accessible  and  ex- 
tensive bedded  deposits  in  the  Tertiary  lake  beds  of  that 
region,  revolutionized  the  industry. 

The  most  important  of  these  beds  is  located  near  Daggett 
(PL  XI,  Fig.  2),  San  Bernadino  County,  California,  but 
much  larger  deposits  are  known  in  Death  Valley.  The 
borax,  which  forms  a  regular  stratum,  interbedded  with 
sands  and  clays,  is  supposed  by  Campbell  (2)  to  have  been 
deposited  in  a  series  of  Tertiary  lakes,  but  the  beds  are 
in  many  instances  tilted,  due  to  violent  crustal  movements, 
which  interrupted  sedimentation  at  intervals. 

Uses.  —  The  borax-bearing  minerals  are  utilized  chiefly 
for  the  manufacture  of  borax  and  boracic  acid.  Borax  is 
used  in  industrial  chemistry,  in  medicine,  and  as  a  labora- 
tory reagent.  It  is  also  employed  in  the  assaying  of  gold 
and  silver  ores. 

Boric  acid  is  used  in  the  manufacture  of  borax,  in  colored 
glazes  for  decorating  iron,  steel,  and  metallic  objects,  in 
enamels  and  glazes  for  pottery,  in  making  flint  glass,  as 
an  antiseptic,  and  as  a  preservative  for  food. 


136 


ECONOMIC  GEOLOGY  OF  THE  UNITED  STATES 


While  several  borax  refineries  are  located  on  the  Pacific 
coast,  the  main  one  is  at  Bayonne,  New  Jersey. 

Production  of  Borax.  —  The  California  colemanite  de- 
posits form  the  main  source  of  domestic  supply,  while  small 
amounts  are  obtained  from  Nevada  and  Oregon. 

The  United  States  production  in  1903  was  34,430  short 
tons  of  crude  borax,  valued  at  $661,400.  The  value  of 
the  refined  product  is  naturally  much  higher,  and  its  total 
value  for  1903  would  be  12,735,000. 

WORLD'S  PRODUCTION  OF  BORAX  IN  1902 


COUNTRY 

QUANTITY 
METRIC  TONS 

MINERAL 

United  States  

18,148 

Calcium  borate 

Bolivia 

593 

Chile       

14,437 

Calcium  borate 

India  (1901) 

162 

Borax 

Germany     

196 

Boracite 

Italv 

2,763 

Peru  (1901)      

4,156 

Calcium  borate 

Turkey 

9000 

Pander  mite 

REFERENCES  ON  BORAX 


(T)  Bailey,  Calif.  State  Mining  Bureau,  Bull.  24 :  33,  1902.  (Calif,  and 
general.)  @  Campbell,  U.  S.  Geol.  Surv.,  Bull.  200, 1902.  (Calif.) 
3.  Kemp,  Min.  Indus.  I:  43,  1893.  (General.)  (t)  Merrill,  Non- 
Metallic  Minerals :  313,  N.  Y.,  1904.  5.  Struthers,  Mineral  Census 
of  1902,  Mines  and  Quarries :  885,  1905.  (General.) 

SODIUM  SULPHATE 

The  hydrous  sulphate,  mirabilite  or  glaubersalt  (Na2SO4 
+  10  H2O),  is  a  white  saline  material,  which  is  collected  on  or 
near  the  surface  of  some  alkaline  marshes  in  desert  regions. 
It  is  known  to  occur  at  several  localities  in  Wyoming. 


SALINES  137 

REFERENCES  ON  SODIUM  SULPHATE 

1.  Attfield,  Jour.  Soc.  Chem.  Ind.,  Jan.  31,  1895.  2.  Knight,  Min. 
Indus.,  Ill :  651,  1895.  3.  Knight,  Wyo.  Agric.  Exper.  Sta.,  Bull. 
14,  1893. 

SODIUM  CARBONATE 

Sodium  carbonate,  or  natural  soda,  is  obtained  by  the 
evaporation  of  the  waters  of  alkali  lakes,  or  is  found  as  a 
deposit  on  or  near  the  surface  of  alkaline  marshes  in  arid  re- 
gions. It  is  usually  a  mixture  of  sodium  carbonate  and 
bicarbonate  in  varying  proportions,  as  well  as  impurities 
such  as  sodium  chloride,  sodium  sulphate,  borax,  and  sodium 
nitrate. 

Sodium  carbonate  is  obtained  from  Owens  Lake  in  Cali- 
fornia. An  analysis  of  the  waters  by  Chatard  yielded : 
SiO2,  .220;  Fe2O3,  A12O3,  .038;  CaCO3,  .055;  MgCO8,  .479; 
KC1,  3.137 ;  NaCl,  29.415 ;  Na2SO4, 11.080 ;  Na2CO3,  26.963 ; 
NaHCO3,  5.725.  The  soda  is  purified  by  fractional  dis- 
tillation. Soda  is  also  known  to  occur  in  Oregon  and 
Nevada. 

REFERENCES  ON  SODIUM  CARBONATE 

1.  Bailey,  Calif.  State  Min.  Bur.,  Bull.  24 :  95, 1902.  2.  Chatard,  U.  S. 
Geol.  Surv.,  Bull.  60 :  27, 1888.  (Analyses.)  3.  Russell,  U.  S.  Geol. 
Surv.,  Mon.  XI :  73. 

SODA  NITER.1 

Soda  niter,  or  Chile  saltpeter  (NaNO3,  with  63.5  per  cent 
Na2O5  when  pure),  is  found  in  San  Bernadino  and  Inyo 
counties,  California,  along  the  shore  lines  marking  the 
boundary  of  Death  Valley  in  Eocene  times  (1).  It  occurs 
in  peculiar  rounded  hills  of  Eocene  clay,  the  niter  being 
found  as  a  layer  near  the  surface  or  distributed  through  the 
1  The  term  niter,  when  used  alone,  refers  to  potash  niter. 


138          ECONOMIC   GEOLOGY   OF  THE  UNITED   STATES 

clay.  Very  little  soda  niter  is  obtained  from  this  source, 
and  the  main  supply  of  this  country  continues  to  come 
from  Chile,  where  extensive  deposits  are  found  in  the 
desert  region  west  of  Iquique.  There  the  niter  (caliche) 
forms  a  bed  6  to  12  feet  thick,  under  a  cap  of  conglom- 
erate (costra)  1  to  18  feet  thick.  The  origin  of  this  deposit 
is  interesting,  and  has  caused  considerable  discussion.  One 
theory  quite  generally  accepted  is  that  the  niter  was  formed 
primarily  by  the  slow  oxidation  in  air  of  guano  or  other 
nitrogenous  organic  matter  in  contact  with  alkali ;  a  second 
theory  refers  its  origin  to  the  oxidation  of  organic  mate- 
rials and  ammonia,  by  microscopic  organisms  known  as 
nitrifying  germs. 

REFERENCES  ON  SODA  NITER 

1.  Bailey,  Calif.  State  Min.  Bur.,  Bull.  24 :  139,  1902. 


PLATE  XII 


FIG.  1.  —  Gypsum  quarry,  Alabaster,  Mich.  Shows  gypsum  overlain  by  glacial 
drift.  The  dump  in  foreground  is  overburden  removed  from  gypsum.  Photo., 
A.  C.  Lane. 


FIG.  2.  —  Rock  phosphate  mine  near  Ocala,  Fla.    Photo.,  A.  W.  Sheaf er. 


CHAPTER  VII 
GYPSUM 

G-ypsum  (1),  the  hydrous  sulphate  of  lime  (CaSO4,  2  H2O), 
occurs  most  frequently  in  sedimentary  rocks,  interbedded 
with  shales,  sandstones,  and  limestones,  and  often  more  or 
less  closely  associated  with  rock  salt.  It  is  also  found  as 
surface  deposits  of  sand  or  mixed  with  clay  (gyp&ite),  as  well 
as  in  limited  quantities  in  volcanic  regions,  especially  in  lavas. 
When  occurring  in  bedded  deposits  (PL  XII,  Fig.  1)  it  is 
massive,  of  finely  crystalline  or  earthy  appearance,  and  of 
variable  color,  although  most  commonly  white  and  gray. 
Transparent,  colorless  forms,  known  as  selenite,  are  found  as 
veins  or  crystals  in  the  massive  gypsum,  or  as  plates  and 
crystals  in  many  clays,  shales,  and  limestones.  This  variety 
by  itself  never  forms  deposits  of  commercial  importance. 

Anhydrite  differs  from  gypsum  chemically  in  the  absence 
of  water,  but  changes  to  it  on  exposure  to  the  air. 

Origin  of  G-ypsum  (3).  —  Gypsum  is  widely  distributed 
both  geographically  and  geologically,  being  found  in  vari- 
ous horizons  from  the  Silurian  to  the  Recent.  Most  beds 
of  this  substance  have  no  doubt  been  formed  by  the  evapo- 
ration of  salt  water  either  in  inland  seas  or  else  in  arms 
of  the  ocean,  the  process  of  precipitation  having  been  dis- 
cussed in  the  chapter  on  Salt.  As  gypsum  separates  from 
sea  water  after  37  per  cent  of  the  water  has  evaporated, 
139 


140          ECONOMIC    GEOLOGY   OF   THE   UNITED   STATES 

while  salt  precipitates  only  after  93  per  cent  has  been 
removed,  it  is  evident  that  gypsum  beds  may  be  deposited 
without  salt.  This  also  explains  why  gypsum  is  more 
widely  distributed  than  salt  ;  and  the  fact  that  the  per- 
centage of  gypsum  in  salt  water  is  much  less  than  that 
of  salt  probably  accounts  for  its  usual  occurrence  in  the 
thinner  deposits. 

Gypsum  may  also  be  formed  by  the  decomposition  of  sulphides, 
such  as  pyrite,  and  the  action  of  the  sulphuric  acid  thus  liberated  on 
lime  carbonate.  Small  quantities  are  formed  in  volcanic  regions 
through  the  action  of  sulphuric  vapors  on  the  lime  of  volcanic  tuffs 
or  other  rocks. 

G-ypsite,  or  gypsum  dirt,  is  an  earthy  or  sandy  variety 
of  gypsum  forming  a  surface  deposit  in  Kansas  (9)  and 
other  western  states  (16,  19),  which,  in  spite  of  its  impure 
appearance,  may  run  high  in  calcium  sulphate.  It  is 
believed  to  be  a  deposit  either  in  the  soil  or  in  shallow 
lakes  supplied  by  springs  whose  water  has  dissolved  the 
calcium  sulphate  from  gypsum  beds  or  other  rocks. 
During  its  precipitation  by  the  second  method,  its  impure 
character  is  caused  by  its  becoming  mixed  with  clay  or 
sand  washed  in  from  the  land. 

Distribution  in  the  United  States  (Fig.  27).  —  Eighteen 
states  are  producers  of  gypsum,  although  four  of  these  — 
Iowa,  Kansas,  Michigan,  and  New  York  —  supply  most  of 
the  output  of  the  country. 

Iowa  (8). — Important  deposits  are  found  in  this  state 
in  an  area  of  about  25  square  miles  in  Webster  County, 
especially  near  Fort  Dodge.  The  gypsum,  which  is  pre- 
sumably of  Permian  age,  rests  on  the  Coal  Measures  and 


GYPSUM  141 

is  covered  by  glacial  drift.  It  varies  from  3  to  30  feet  in 
thickness,  with  an  average  of  16  feet,  and  much  of  it  is 
sufficiently  white  for  stucco. 

Kansas.  —  Gypsum  (9)  is  found  occurring  either  as  rock 
gypsum,  or  as  gypsite,  the  deposits  forming  a  belt  extend- 
ing across  the  central  part  of  the  state  in  a  northeast- 
southwest  direction,  and  includes  three  important  areas. 


FIG.  27.  —  Map  showing  gypsum-producing  localities  of  United  States.    After 
Adams,  U.  S.  Geol.  Surv.,  Bull.  223. 

The  beds  of  rock  gypsum  are  of  Permian  age,  interbedded 
with  red  shales,  those  at  the  southern  end  of  the  belt  being 
stratigraphically  1000  feet  higher  than  those  at  the  northern 
end. 

The  gypsite  or  gypsum  dirt,  which  is  of  more  recent  age, 
is  found  in  the  central  area,  as  well  as  at  a  number  of 
other  localities.  The  spring  waters  which  have  supplied  it 
have  leached  the  calcium  sulphate  either  from  the  gypsum 


142          ECONOMIC   GEOLOGY   OF  THE  UNITED   STATES 

beds  or  the  red  shales.  The  product  is  used  for  fertilizer 
and  cement  plaster. 

Deposits  of  gypsum  earth  are  found  to  the  south  of 
Kansas  in  Oklahoma  (16)  and  northern  Texas  (16),  as  well 
as  to  the  northwest  in  Wyoming1  (19,  20). 

Michigan  (10)  contains  two  important  occurrences  of  gyp- 
sum, one  in  the  vicinity  of  Grand  Rapids,  and  the  other  at 
Alabaster  on  Saginaw  Bay  (PI.  XII,  Fig.  1),  both  in  beds 
of  Lower  Carboniferous  age.  That  at  Grand  Rapids  runs 
from  6  to  12  feet  in  thickness,  forming  several  beds  inter- 
stratified  with  shale  and  limestone.  A  third  possibly  pro- 
ductive area  is  near  St.  Ignace  on  the  upper  peninsula,  where 
it  occurs  in  the  Salina. 

New  York  (11, 12).  —  Gypsum  occurs  in  the  Salina  shales 
of  central  and  west  central  New  York.  Most  of  the  product 
is  gray  and  used  for  land  plaster ;  but  in  recent  years  some 
whiter  deposits,  suitable  for  stucco,  have  been  worked  near 
Batavia. 

Other  Occurrences.  —  Gypsum  is  also  found  in  beds  of 
Lower  Carboniferous  age  in  the  Holston  Valley  of  south- 
western Virginia  (18).  The  rock  is  mined  partly  by  under- 
ground workings,  and  some  of  the  beds  are  fully  30  feet 
thick.  The  product  is  used  for  land  and  wall  plaster.  In 
Ohio  gypsum  has  been  obtained  from  the  lower  Helderberg 
beds  of  Ottawa  County,  10  miles  west  of  Sandusky.  The 
material  occurs  at  different  horizons,  the  beds  being  bent 
into  rolls,  the  main  ones  having  a  thickness  of  about  12  feet 
(13,  16).  Additional  occurrences  are  known  in  Wyoming 
( 19,  20),  Utah  (17),  Arizona  (5),  Nevada  (16),  California  (6), 
lontana  (16),  Idaho  (16),  Colorado  (7,  16),  and  South  Da- 
,  >ta  (H-16). 


GYPSUM 


143 


Analyses.  —  The   following    analyses    indicate    the    com- 
position of  gypsum  from  different  localities  in  the  United 

States :  — 

ANALYSES  OF  GYPSUM  FROM  UNITED  STATES 


CaO 

80s 

H,0 

Insolu- 
ble 

CaCOa 

Al,03 

Fe,0. 

MgO 
.54 

.16 
.42 

CO, 
2.03 

Pure  Gypsum    . 

Onondaga,  N.Y. 
Sandusky,  O.     . 
Upper  layer, 
Fort  Dodge,  la. 
Michigan  .     .     . 
Medicine  Lodge, 
Kas.      ... 
Gypsite,  Salina, 
Kas.      .     .     . 
Gypsite,  Quanah, 
Tex.      .     .     . 
Plastercoj  Va.    . 

32.60 

46.50 

20.90 

4.64 
.91 

.65 

.19 
12.13 

7.43 
.10 

21.44 
5.07 

.60 

.1 
.£ 

.] 

.7 

,  ' 
0 

9 

2 
0 

32.35 

73.92 
46.38 

19.70 

20.76 
20.98 

20.46 
16.75 

8.49 
19.40 

78 
32.88 

32.53 
29.14 

44 

45.79 

45.73 
37.49 

78 
33.20 

66 
46.04 

Uses  (1).  —  Gypsum  is  sold  either  in  the  ground,  uncal- 
cined  condition,  or  after  calcining  and  screening.  In  the 
former  state  its  chief  value  is  as  a  fertilizer,  it  being  marketed 
under  the  name  of  land  plaster,  which  is  also  used  as  a  dis- 
infectant. Though  the  softness  of  gypsum  prevents  its 
general  employment  as  a  building  material,  the  pure  white, 
massive  varieties,  known  as  alabaster,  have  been  used  for 
statuary,  basins,  vases,  and  other  objects  for  interior  decora- 
tion. Gypsum  is  also  used  to  weight  fertilizers,  and  as  an 
absorbent  of  organic  materials  in  them;  as  a  flux  in  the 
manufacture  of  glass  and  porcelain;  and,  under  the  name 
of  '•'•terra  alba"  as  an  adulterant  of  foods  and  medicinal 
preparations. 


144 


ECONOMIC  GEOLOGY  OF  THE  UNITED  STATES 


In  its  calcined  form,  gypsum  is  known  as  plaster  of 
paris  and  has  the  following  uses,  dependent  on  its  prop- 
erty of  hardening  or  setting  when  mixed  with  water : 
stucco,  plastering  for  walls,  whitewash,  pottery  molds, 
statuary,  and  dental  purposes,  as  a  deodorizer,  for  crayons, 
and  as  a  retarder  of  fermentation  and  absorbent  of  water 
in  wines. 

Calcining  Gypsum.  —  When  heated  to  250°  F.,  gypsum  loses  a  portion 
of  its  water  of  hydration,  but  if  finely  ground  has  the  property  of 
recombining  with  it.  If  heated  to  300°  F.  to  400°  F.,  it  loses  this  power 
and  is  said  to  be  dead-burned.  In  addition  to  dehydration,  burning  also 
breaks  up  the  crystals  into  minute  particles.  The  set  is  due  to  the  for- 
mation of  a  crystalline  network  of  the  rehydrated  grains. 

Since  calcined  gypsum  sets  in  from  6  to  10  minutes,  some  retarding 
material,  such  as  organic  matter  from  slaughter-house  refuse,  is  often 
added  to  it,  and  thus  the  setting  process  may  be  delayed  from  2  to  6 
hours.  Those  plasters  which  set  slowly  are  termed  cement  plasters. 

The  following  analyses  show  the  composition  of  (1)  uncalcined  gyp- 
sum ;  (2)  the  calcined  rock ;  and  (3)  the  plaster  after  it  has  taken  up 
water  and  set.  From  these  it  will  be  seen  that  the  plaster  takes  up  the 
amount  of  water  lost  in  calcination. 


SERIES  OF  ANALYSES  SHOWING  CHANGES  IN  GYPSUM  DURING 
BURNING  AND  AFTER  SETTING 


CRUDE 

FINISHED 

SET 

SiO2  and  Insol.  res  
Fe2O3  and  A12O3    
CaO 

12.29 
2.27 
2967 

14.31 
2.16 
3353 

12.03 
1.62 
3005 

MeO 

78 

91 

61 

SO3       

3487 

3985 

35.73 

CO 

3  52 

4  11 

355 

^^2  
H9O      

1607 

481 

16.38 

GYPSUM 


145 


Production  of  Gypsum.  —  Michigan,  New  York,  Iowa,  and 
Kansas  are  the  four  leading  producers,  but  many  other  states 
contribute  small  amounts  as  seen  below. 

PRODUCTION  OF  GYPSUM  IN  UNITED  STATES  FROM  1901-1903 


1901 

1902 

1903 

SHORT 
•  TONS 

VALUE 

SHORT 
TONS 

VALUE 

SHORT 
TONS 

VALUE 

California,  Ohio, 

and  Virginia 

18,7861 

$49,3441 

101,545 

$290,393 

103,392 

$467,113 

Colorado  and 

Wyoming     . 

17,394 

76,435 

16,051 

73,372 

33,549 

133,347 

Iowa,    Kansas, 

and  Texas    . 

213,419 

629,336 

295,769 

807,355 

307,102 

1,087,045 

Michigan     .     . 

185,150 

267,243 

240,227 

459,621 

269,093 

700,912 

New  York    .     . 

119,565 

241,669 

110,364 

259,170 

137,886 

462,383 

Oklahoma    .     . 

15,930 

66,031 

34,156 

111,215 

69,158 

234,621 

Other  states      . 

63,547 

176,583 

18,366 

88,215 

121,524 

707,522 

Total   .     .     . 

633,791 

$1,506,641 

816,478 

$2,089,341 

1,041,"04 

$3,792,943 

The  imports  for  1903  amounted  to  269,484  short  tons, 
valued  at  1378,597. 

WORLD'S  PRODUCTION  OF  GYPSUM,  1902 


SHORT  TONS 

VALUE 

France   

1,975,513 

83,318,070 

United  States      

816  478 

2  089  341 

332  045 

356  317 

Great  Britain      

251  699 

384263 

34  944 

12732 

Algeria  

6889 

59953 

7  874 

17  443 

Total2     

3  425  372 

^6  230  419 

1  Ohio,  none  reported. 

L 


2  India  not  available. 


146          ECONOMIC   GEOLOGY  OF  THE   UNITED   STATES 


REFERENCES  ON  GYPSUM 

PROPERTIES  AND  TECHNOLOGY.  1.  Grimsley,  Mich.  Geol.  Surv.,  IX, 
Ft.  2,  1904.  2.  Grimsley  and  Bailey,  Kas.  Geol.  Surv.,  V,  1899. 
3.  Wilder,  Eng.  and  Min.  Jour.,  LXXIV:  276,  1902. 

AREAL.  4.  Adams  and  others,  U.  S.  Geol.  Surv.,  Bull.  223,  1904. 
(United  States.)  —  Arizona :  5.  Blake,  Amer.  Geol.,  XVIII:  394, 
1896.  — California:  6.  Crawford,  Calif.  State  Mining  Bureau,  XII : 
323, 1894.  —  Colorado  :  7.  Lee,  Stone,  XXI :  35, 1900.  (Larimer  Co.)— 
Iowa :  8.  Wilder,  la.  Geol.  Surv.,  XII :  99,  1902,  and  Jour.  Geol., 
XI :  723,  1903.  —  Kansas  :  9.  Grimsley  and  Bailey,  Kas.  Univ.  Geol. 
Surv.,  V,  1899.  —  Michigan :  10.  Grimsley,  Mich.  Geol.  Surv.,  IX, 
Pt.  2,  1904.  —  New  York :  11.  Merrill,  N.  Y.  State  Museum,  Bull. 
11 :  70,  1893.  12.  Parsons,  N.  Y.  State  Geologist,  20th  Ann.  Kept. : 
r  177,  1902.— Ohio:  13.  Orton,  Ohio  Geol.  Surv.,  VI:  696,  1888.— 
South  Dakota:  14,  U.  S.  Geol.  Surv.,  Geol.  Atlas  Folios  85:  6. 
15.  Todd,  S.  D.  Geol.  Surv.,  Bull.  3:  99,  1902.  — United  States:  16. 
Adams  and  others,  U.  S.  Geol.  Surv.,  Bull.  223,  1904.  — Utah:  17. 
Boutwell,  U.  S.  Geol.  Surv.,  Bull.  225:  483,  1904.  — Virginia: 

18.  Eckel,   U.   S.   Geol.   Surv.,  Bull.   213:  406,  1903.  —  Wyoming : 

19.  Knight,  Wyo.  Exper.  Station,  Bull.  14 :  189,  1893.     20.  Slosson 
and  Moody,  Wyo.  Coll.  Agric.  and  Mech.,  10th  Ann.  Kept.,  1902. 


CHAPTER  VIII 
FERTILIZERS 

UNDER  this  term  are  included  a  number  of  mineral  sub- 
stances, limestone,  marl,  gypsum,  phosphate  of  lime,  green- 
sand,  and  guano,  which  are  of  value  for  adding  to  the  soil  to 
increase  its  supply  of  plant  food.  Since  the  first  three  of 
these  have  other  uses  as  well,  they  have  already  been  dis- 
cussed in  Chapters  III,  V,  and  VII. 

Phosphate  of  Lime.  —  This  occurs  both  as  crystalline  phos- 
phate of  lime,  or  apatite,  and  amorphous  phosphate  of  lime, 
or  rock  phosphate. 

Apatite  (5,  6).  —  This  mineral,  which  theoretically  contains 
42.3  per  cent  P2O6,  is  widely  distributed  in  some  igneous 
and  metamorphic  rocks,  but  rarely  occurs  in  sufficient  quan- 
tity, or  in  sufficiently  concentrated  masses,  to  render  its 
extraction  profitable,  at  least  while  the  supply  of  amorphous 
phosphate  lasts.  No  commercial^  valuable  deposits  have 
thus  far  been  discovered  in  the  United  States;  but  in  the 
provinces  of  Quebec  and  Ontario,  Canada,  apatite  occurs  in 
veins  or  pockets  in  metamorphic  rocks,  though  little  is  now 
mined. 

Amorphous  Phosphates.  —  These,  though  composed  chiefly 
of  phosphate  of  lime,  also  carry  variable  quantities  of  other 
substances.     (See  table,  p.  154.)     They  occur  (1)  as  con- 
cretionary bodies  in  consolidated  rocks  ;  (2)  as  beds ;  (3)  as 
147 


148 


ECONOMIC  GEOLOGY  OF  THE  UNITED  STATES 


irregular  rocklike  masses ;  and  (4)  as  nodular  masses  of 
varying  size,  often  scattered  through  unconsolidated  beds. 
As  is  shown  in  the  following  descriptions,  amorphous  phos- 
phates occur  in  various  geological  horizons,  from  the  Silurian 
to  Tertiary,  and  in  several  states  in  the  Union,  though 
most  of  the  domestic  supply  comes  from  Florida,  Tennessee, 
and  South  Carolina. 

Florida  Phosphates  (10). — This  state  is  at  present  the 
most  important  phosphate  producer,  although  the  full  extent 
and  value  of  the  deposits  were  unsuspected  until  the  dis- 
covery of  large  beds  along 
the  Peace  River  in  1887. 
The  phosphate  deposits 
which  are  associated  with 
Tertiary  limestones  of  vari- 
ous horizons  from  the  Eocene 
to  the  Pliocene  form  a  curved 
belt,  beginning  west  of  the 


Appalachicola  River  and  ex- 
tending east  and  then  south 
through  Dunnellon,  and  ap- 
proximately as  far  as  Punta 
Gorda  (Fig.  28).  The  to- 
pography varies  from  gently 
FIG.  28.  —  Map  of  Florida  phosphate  rolling  to  flat  pine  lands  and 


"eas,  the  general 
elevation  being  under  75  feet. 

Eldridge  recognizes  four  types  of  phosphates  in  this  area, 
viz.  hard  rock,  soft  rock,  land  pebble,  and  river  pebble.  Of 
these  the  hard  rock  phosphate  (PL  XII,  Fig.  2)  is  the  richest, 
and  has  had  most  influence  in  the  rapid  development  of  the 


FERTILIZERS  149 

district.  It  is  a  hard,  massive,  close-textured  rock,  of  vari- 
able color,  and  often  containing  irregular  cavities  which 
show  a  secondary  deposition  of  phosphate.  Accompanying 
this  in  some  places  is  a  second  type,  the  soft  phosphate, 
which  is  evidently  a  disintegration  product.  Bowlders  of 
hard  phosphate  are  frequently  embedded  in  a  matrix  of  soft 
phosphate,  and  also  in  sands  and  clays  overlying  the  Eocene 
limestone.  While  the  hard  rock  has  an  average  of  a  little 
over  36.65  per  cent  of  phosphoric  acid,  the  soft  phosphate 
rarely  averages  over  22.90. 

The  land  pebble  or  matrix  rock  is  made  up  of  pebbles  of 
varying  size,  shape,  and  color,  and  composed  either  (1)  of 
earthy  material  with  fossils,  quartz  grains,  and  pisolitic 
grains  of  phosphate,  or  (2)  of  pebbles  closely  resembling 
the  hard-rock  phosphate.  To  render  it  marketable,  the 
pebbles,  which  average  32.06  per  cent  phosphoric  acid,  have 
to  be  freed  from  the  matrix  by  washing  and  screening.  The 
unit  composition  of  sale  for  land  pebble  is  68  per  cent  of  the 
bone  phosphate  and  3  per  cent  of  the  combined  oxides  of 
iron  and  alumina,  with  moisture  at  2  per  cent. 

The  river  pebble  consists  of  phosphate  pebbles,  having  a 
blue,  black,  or  dark  gray  surface,  and  mixed  with  sand, 
bones,  and  teeth.  It  is  found  in  the  present  as  well  as  in 
ancient  river  channels,  in  the  latter  case  being  covered  by 
coastal  sands.  That  found  in  the  Peace  River  district 
averages  28.40  per  cent  phosphoric  acid. 

All  of  the  above-mentioned  types,  with  the  exception 
of  the  soft  phosphates,  are  found  underlying  more  or  less 
separate  regions  (Fig.  28). 

The  origin  of  the  Florida  phosphates  has  been  a  puzzling 
problem  to  geologists.  Eldridge  (10)  has  proposed  two 


150          ECONOMIC   GEOLOGY  OP  THE   UNITED   STATES 

theories :  (1)  that  they  have  been  derived  by  the  leaching 
of  guano  and  bone  beds,  and  the  deposition  of  the  phosphate 
in  the  underlying  limestone,  either  by  precipitation  in  its 
pores  or  replacement  of  the  lime  carbonate ;  (2)  that  they 
are  due  to  the  solution  of  the  limestone  and  consequent 
concentrations  of  the  less  soluble  phosphate  of  lime  which 
was  originally  disseminated  through  the  rock.  Later  solu- 
tions removed  the  limestones  from  around  the  phosphate 
deposits,  leaving  them  as  bowlders,  which,  at  a  still  later 
date,  were  rounded  by  water  currents  which  also  deposited 
sand  around  them. 

The  land  pebble  and  river  pebble  probably  represent 
nodules  of  a  highly  phosphatized  marl,  formed  in  limestone 
pebbles,  shell  casts,  or  by  segregation  of  the  contained  lime 
phosphate,  and  subsequently  set  free  by  the  solution  of  the 
lime  carbonate. 

South  Carolina  Phosphates.  —  Phosphate  is  found  both  on 
the  land  and  in  the  river  bottoms  in  a  belt  about  60  miles 
long  lying  inland  from  Charleston  and  Beaufort  (6,  17,  18). 
The  phosphate,  which  rarely  averages  much  over  one  foot  in 
thickness,  is  commonly  of  nodular  character,  and  often  con- 
tains many  bones  and  teeth.  The  presence  of  these  animal 
remains,  including  both  land  and  marine  forms,  has  given 
rise  to  the  belief  that  the  deposits  were  caused  by  the  accu- 
mulation of  bones  and  excrements  along  a  shore  line,  prob- 
ably of  Upper  Miocene  age.  Leaching  of  these  remains 
may  have  permitted  a  later  replacement  of  limestone  or  the 
formation  of  phosphatic  concretions  in  swamp  bottoms. 

Tennessee  Phosphates  (11,12,13,16,19).  —  Since  the  recogni- 
tion, in  1893,  of  considerable  quantities  of  high-grade  phos- 
phates in  western  middle  Tennessee  (Fig.  29),  there  have 


FERTILIZERS 


151 


been  important  developments  of  the  deposits.  Three  types 
are  recognized.  The  first  is  brown  phosphate  occurring  in 
terraces  along  Duck  River,  Maury  County.  It  is  evidently 


Black  Phosphate 


White  Phosphate 
Brown  Phosphate 


F^a  Area  in  which  Black 
^-^  Phosphate  may  be  found 

FIG.  29.  — Map  of  Tennessee  phosphate  areas.    Compiled  from  data  in  U.  S.  Geol. 
Surv.,  Columbia  Atlas  folio,  and  papers  by  Hayes. 

derived  from  the  weathering  of  near-by  phosphatic  limestone 
of  Ordovician  age. 

A  second  type,  of  black  or  blue  color,  occurs  either  in 
nodules  or  in   beds.     The  bedded  phosphate  is  underlain 


152 


ECONOMIC    GEOLOGY   OF   THE    UNITED   STATES 


either  by  gray  Devonian  sandstone  or  by  blue  Silurian  lime- 
stone, and  capped  by  black  carbonaceous  shale ;  the  nodular 

form  occurs  higher 
up  in  the  section. 
Both  are  believed 
to  be  chemical  pre- 
cipitates on  the 
floor  of  the  Devo- 
nian sea. 

The  third  group 
includes  white 
phosphates  occur- 
ring in  three  con- 
ditions: stony, 
brecciated,  and 
lamellar,  inti- 
mately associated 
with  Carbonifer- 
ous strata,  but 
some  occur  in  Si- 
lurian limestones. 
In  the  stony  phase, 
the  phosphate  has 
been  deposited  in 
a  siliceous  lime- 
stone, replacing 
the  lime.  It  al- 
ternates with  beds 

FIG.  30.  — Vertical  section  showing  geologic  position      °f  stony  chert  and 
of  Tennessee  phosphates.    After  Hayes.  contains  under  50 

per  cent  of  bone  phosphate.     The  brecciated  form,  which 


NCONFORMITY 

FERNVALE  FORMATION 
SHALES  AND  LIMESTONE 
TV 


FERTILIZERS  153 

is  the  most  abundant,  consists  of  angular  chert  fragments  in 
a  phosphate  matrix  deposited  between  chert  fragments  of  a 
limestone.  The  lamellar  variety  was  deposited  in  caverns 
in  the  Silurian  limestones,  which,  since  the  deposition  of  the 
phosphate,  has  weathered  to  a  residual  clay  in  which  the 
phosphate  masses  occur. 

Hayes  has  advanced  the  .theory  that  the  lime  phosphate 
of  the  white  phosphates  was  originally  extracted  from  sea 
water  by  organisms,  and  accumulated  on  the  bottom  either 
as  nodules  or  disseminated  through  the  sediments.  Later, 
when  these  strata  were  lifted  above  sea  level  and  subjected 
to  erosion  and  the  action  of  percolating  waters  charged  with 
acids  from  the  soil,  the  phosphate  was  leached  out  and 
carried  to  lower  levels  where  it  was  redeposited  either  in 
ca\dties  or  by  replacing  limestone. 

Other  Phosphate  Occurrences,  —  Phosphate,  in  the  form  of 
nodules,  white  vesicular  rock,  and  in  limestone  fragments, 
occurs  along  the  contact  of  Oriskany  sandstone  and  Lower 
Helderberg  limestone,  in  Juniata  County,  Pennsylvania  (14). 
It  contains  30  to  54  per  cent  bone  phosphate.  Nodular  phos- 
phate, although  not  worked,  is  known  to  occur  in  Devonian 
strata  in  Arkansas  (7),  and  in  Cretaceous  and  Tertiary  strata 
in  Alabama  (20),  Georgia  (15),  and  North  Carolina  (8). 

Composition.  —  The  following  analyses  will  serve  to  show 
the  composition  of  some  native  phosphates.  Of  the  impuri- 
ties present,  lime  carbonate  is  undesirable,  since  it  neutral- 
izes the  acid  used  in  phosphate  manufacture.  Iron  oxide, 
alumina,  and  silica  are  inert  impurities  displacing  just  so 
much  phosphate  of  lime. 

The  richness  of  a  phosphate  is  usually  expressed  in  terms 
of  the  tribasic-calcic  phosphate,  commonly  termed  bone 


154 


ECONOMIC   GEOLOGY   OF   THE   UNITED   STATES 


phosphate.     Of   this   about   45.80   per   cent  is  phosphoric 

acid. 

ANALYSES  OF  PHOSPHATE  ROCK 


I 

$ 

4 

S 

0* 

| 

1 

3 

0 

o 
5 

+  s 

Ej 

i  1 

MISCKL.  I 

TENNESSEE 

Mt.  Pleasant  .     . 

1.05 

34.69 

2.39 

3.36 

1.40 

3.18 

4.05 

2.64 

46.76 

1.39 

76.42 

S 

Swan  Creek, 

Hickman  Co.    . 

.50 

28.27 

3.14 

2.93 

1.15 

13.24 

40.50 

2.80 

White  phosphate, 

Stone     Quarry 

Hollow,    Perry 

Co 

15.30 

8.23 

54.88 

22.76 

FLORIDA 

.30 

Hard  rock  .     .     . 

.07 

38.84 

.96 

3.07 

.65 

.49 

2.96 

50.08 

2.46 

Washed  land  peb- 

.21 

ble  

.63 

34.72 

1.35 

2.53 

2.19 

4.34 

2.72 

47.95 

3.15 

.44 

River  pebble   .    . 

.56 

28.33 

1.05 

2.01 

3.99 

12.23 

4.90 

42.75 

2.44 

SOUTH  CAROLINA 

Average,     S.     C. 

Analysis  .    .    . 

3.68 

25.61 

4.68 

11.55 

4.78 

55.91 

Uses.  —  Fertilizers  are  used  either  in  their  raw  condition 
or  after  undergoing  proper  preparation.  Lime  carbonate  is 
commonly  calcined  before  being  spread  on  the  soil,  while 
gypsum  is  first  pulverized  before  being  sold  as  land  plaster. 

Phosphate  rock  is  treated  with  sulphuric  acid  to  produce  superphos- 
phate or  acid  phosphate,  and  in  this  treatment  ammoniates,  or  potash,  or 
both,  are  sometimes  added  to  the  material.  Concentrated  phosphate  is 
made  by  treating  the  phosphate  rock  with  enough  sulphuric  acid  to 
entirely  decompose  it,  converting  all  the  lime  into  sulphate,  the  phos- 
phoric acid  solution  being  drawn  off  and  further  treated  with  additional 
quantities  of  high-grade  phosphate.  Since  this  form  of  phosphate  there- 
fore requires  raw  materials  of  a  high  grade,  and  is  much  more  exten- 
sively manufactured  in  Europe  than  in  the  United  States,  most  of  the 
high-grade  Florida  rock  is  exported. 


FERTILIZERS  155 

Guano.  —  Under  this  name  are  included  surface  deposits 
of  excrement,  chiefly  of  birds.  Penrose  (25)  recognizes  two 
classes :  (1)  soluble  guano,  of  recent  origin,  which  still  con- 
tains most  of  its  soluble  ingredients;  (2)  leached  guano, 
which  has  lost  its  soluble  constituents  by  the  action  of  rain 
or  sea  water.  Most  of  the  soluble  guano  of  commerce  was 
formerly  obtained  from  Peru,  where,  it  is  said,  the  Incas,  as 
well  as  the  early  Spaniards,  valued  it  so  highly  that  a  death 
penalty  was  imposed  for  killing  the  birds  which  produced  it. 
These  deposits,  from  which  many  thousand  tons  have  been 
obtained,  are  now  exhausted.  No  large  deposits  of  bird 
guano  are  known  in  the  United  States.  Leached  guanos  occur 
on  islands  in  the  southern  Pacific  and  in  the  West  Indies. 

Bat  guano  has  been  found  in  the  caves  of  Kentucky, 
Texas  (26),  and  many  other  states,  but  few  of  the  deposits 
have  proved  large  enough  to  work,  and  none  are  of  great 
extent,  although  one  cave  in  Texas  was  known  to  yield 
1000  tons.  The  following  analysis  is  representative:  am- 
monia, 9.44  per  cent;  available  phosphoric  acid,  3.17  per 
cent;  potash,  1.32  per  cent. 

Greensand.  —  This  term  is  applied  to  beds  of  marine 
origin,  made  up  in  large  part  of  the  green  sandy  grains  of 
glauconite,  the  hydrated  silicate  of  iron  and  potash.  It 
also  contains  small  amounts  of  phosphoric  acid.  Green- 
sands  (23)  are  found  at  many  localities  in  the  Cretaceous 
and  Tertiary  formations  of  the  Atlantic  Coastal  Plain,  but 
New  Jersey  (22)  and  Virginia  are  the  two  important  pro- 
ducers. The  New  Jersey  greensand  is  spread  on  the  soil 
in  its  raw  condition,  but  that  from  Virginia  is  dried  and 
ground  for  use  in  commercial  fertilizers. 


156 


ECONOMIC   GEOLOGY   OF   THE   UNITED   STATES 


The  following  analyses  show  its  variable  composition,  and 
the  comparatively  small  amount  of  P2O5  and  K2O  neces- 
sary to  make  it  of  value  as  a  fertilizer. 

ANALYSES  OF  GREENSAND 


P.O. 

SO, 

SiO, 

CO, 

K,0 

Na,O 

CaO 

MgO 

Al,08 

Fe,0» 

H,0 

Pemberton, 

N.  J.  .    .    . 

1.02 

.27 

50.23 

— 

6.32 

1.59 

1.40 

3.45 

7.94 

20.14 

9.00 

Aquia  Creek, 

Va.    .    .    . 

.09 

— 

21.58 

29.79 

.37 

.59 

36.78 

1.05 

7.70 

.76 

Production  of  Fertilizers.  —  The  production  of  phos- 
phate in  the  United  States  for  several  years  was  as 
follows :  — 


1901 

1902 

1903 

LONG  TONS 

VALUE 

LONG  Toxs 

VALUB 

LONG  TONS 

VALUE 

Florida    .    . 
South 
Carolina   . 
Tennessee     . 
Others      .    . 

Total    .    . 

751,996 

321,181 
409.653 
893 

$3,159,473 

961,840 
1,192,090 
3,000 

785,430 

313,365 
390,799 
720 

$2,564,197 

919,725 
1,206,647 
2,875 

860,336 

258,540 
460,530 
2,125 

$2,986,824 

783,803 
1,543,567 
4,600 

1,483,723 

85,316,403 

1,490,314 

$4.693,444 

1,581,576 

$5,319,294 

The  imports  of  crude  phosphates,  guano,  and  fertilizers 
in  1903  were  valued  at  $985,324.  The  world's  production 
in  1902,  exclusive  of  Norway  and  Russia,  was  2,766,253 
metric  tons,  valued  at  $9,778,950.  The  production  of  gyp- 
sum is  given  under  that  head.  Greensand  statistics  are 
not  available. 


FERTILIZERS  157 


REFERENCES  ON  FERTILIZERS 

GENERAL.  1.  Adams,  Amer.  Inst.  Min.  Engrs.,  Trans.  XVIII:  649,  1890. 
(List  of  Commercial  Phosphates.)  2.  Davidson,  Eng.  and  Min.  Jour., 
LIU:  499,  1892.  (Deep  Sea  Formations.)  3.  Davidson,  Amer.  Inst. 
Min.  Engrs.,  Trans.  XXI :  139,  1893.  (United  States  and  Canada.) 
4.  Matthew,  N.  Y.  Acad.  Sci.,  Trans.  XII:  108,  1893.  (Nodules 
of  Cambrian.)  — APATITE:  5.  Ells,  Can.  Rec.  Sci.,  VI:  213,  1895. 
(Canada.)  6.  Penrose,  U.  S.  Geol.  Surv.,  Bull.  46,  1888.  (General.)  — 
PHOSPHATES:  7.  Branner,  Amer.  Inst.  Min.  Engrs.,  Trans.  XXVI: 
580,  1897.  (Arkansas.)  8.  Carpenter,  N.  Ca.  Agric.  Exper.  Station, 
Bull.  110,  1894.  (North  Carolina  marls  and  phosphates.)  9.  Eckel, 
U.  S.  Geol.  Surv.,  Bull.  213:  424,  1903.  (Decatur  County,  Tenn.) 
10.  Eldridge,  Amer.  Inst.  Min.  Engrs.,  Trans.  XXI:  196,  1893. 
(Florida.)  11.  Hayes,  U.  S.  Geol.  Surv.,  21st  Ann.  Kept.,  Ill:  473, 
1901.  12.  Also  17th  Ann.  Kept.,  II:  513,1896.  13.  Hayes,  16th  Ann. 
Kept.,  IV :  610,  1895.  (Tennessee  white  phosphates.)  14.  Ihlseng, 
U.  S.  Geol.  Surv.,  17th  Ann.  Kept.,  III.  (ctd.)  :  955,  1896.  (Penn- 
sylvania.) 15.  McCallie,Ga.  Geol.  Stirv.,  Bull.  5-A,  1896.  (Georgia.) 
16.  Memminger,  U.  S.  Geol.  Surv.,  Min.  Res.,  1893:  709,  1894. 
(Tennessee.)  17.  Penrose,  U.  S.  Geol.  Surv.,  Bull.  46,  1888. 
18.  Reese,  Amer.  Jour.  Sci.  iii,  XLIII :  402,  1892.  (South  Caro- 
lina.) 19.  Phillips,  Eng.  and  Min.  Jour.,  LVII :  417,  1894.  (Hick- 
man  County,  Tennessee.)  20.  Smith,  Ala.  Geol.  Sur.,  Bull.  2 :  9, 
1892.  (Alabama.)  —  GREENSAND  :  21.  Clark  and  Martin,  Md.  Geol. 
Surv.,  Rept.  on  Eocene,  1901.  (Maryland.)  22.  Cook,  Geol.  of  N.  J., 
1868:  261,  1868.  23.  Parsons,  U.  S.  Geol.  Surv.,  Min.  Res.,  1901: 
823,  1902.  (General.)  24.  Wilber,  U.  S.  Geol.  Surv.,  Min.  Res., 
1882:  522,  1883.  (United  States.)  —  GUANO:  25.  Penrose,  U.  S. 
Geol.  Surv.,  Bull.  46  :  117,  1898.  26.  Phillips,  Mines  and  Minerals, 
XXI :  440,  1901.  (Texas  Bat  Guano.) 


CHAPTER  IX 
ABRASIVES 

Introductory.  —  Under  this  heading  are  included  natural 
products  employed  for  abrasive  purposes;  but  brief  refer- 
ence will  also  be  made  to  some  artificial  compounds  which 
come  into  serious  competition  with  the  natural  ones. 

The  natural  abrasives  may  be  divided  into  the  three  fol- 
lowing groups :  (1)  Those,  like  grindstones,  whetstones, 
and  buhrstones,  which  occur  in  the  form  of  massive  rock, 
and  which  can  consequently  be  cut  and  manufactured 
directly  into  the  desired  shape;  (2)  those,  like  garnet, 
emery,  quartz,  and  corundum,  which  occur  usually  as 
grains  in  a  rock  or  vein,  and  which  have  to  be  separated 
mechanically  from  the  rock;  and  (3)  those,  like  infusorial 
earth,  quartz  sand,  and  pumice  dust,  which  occur  in  more 
or  less  unconsolidated  condition. 

While  some  abrasive  substances  occur  as  constituents  of 
veins,  the  great  majority  form  a  part  of  rocks  of  either 
sedimentary,  igneous,  or  metamorphic  origin.  That  they 
are  widely  distributed  both  geologically  and  geographically 
is  shown  in  the  following  description  of  the  individual 
groups,  and  the  map  (Fig.  31) :  — 

Grindstones  (2,  3).  —  These  are  made  from  sandstones  of 
homogeneous  texture  and  sufficient  cementing  material  to 
hold  the  quartz  grains  together,  but  not  enough  to  so  fill 
158 


PLATE  XTIT 


FIG.  1.  —  Grindstone  quarry,  Tippecanoe,  Ohio.    J.  H.  Pratt,  photo. 


FIG.  2.  —  Corundum  vein  between  peridotite  and  gneiss,  Corundum  Hill,  Ga. 
After  Pratt,  U.  S.  Geol.  Surv.,  Bull.  180. 


ABRASIVES 


159 


the  pores  as  to  make  the  rock  wear  smooth  under  use. 
Most  of  the  grindstones  produced  in  the  United  States  are 
obtained  from  the  Berea  grit  of  Ohio  (PL  XIII,  Fig.  1)  and 
Michigan,  certain  layers  of  which  are  highly  prized  for 
this  purpose. 


FIG.  31.  —  Map  showing  distribution  of  abrasives  in  United  States. 

Pulpstones,  which  have  a  diameter  of  48  to  56  inches,  a  thickness 
of  16  to  26  inches,  and  a  weight  of  2300  to  4800  pounds,  are  a  thicker 
variety  of  grindstone.  They  are  used  for  grinding  wood  pulp  in  paper 
manufactui'e,  and  hence  have  to  withstand  continual  exposure  to  hot 
water.  On  account  of  their  superior  quality,  pulpstones  from  New- 
castle-upon-Tyne,  England,  supply  most  of  the  American  demand ;  but 
it  is  probable  that  certain  beds  of  the  Ohio  sandstones  will  be  found 
suited  for  this  purpose  (3). 

Whetstones,  Oilstones  (2,  3,  10,  11),  etc. —  The term  "whet- 
stone "  includes  those  stones  used  for  sharpening  tools,  the 
term  "oilstone"  being  often  applied  when  oil  is  placed  on 
the  stone  to  prevent  heating  and  clogging  of  the  pores  by 


160          ECONOMIC   GEOLOGY   OF  THE  UNITED   STATES 

grains  of  steel.  The  stones  used  for  making  whetstones 
are  either  sedimentary  or  metamorphic  in  character,  and 
include  sandstone,  quartzite,  mica  schist,  and  novaculite. 
The  stone  selected  will  naturally  vary  somewhat  with  the 
exact  use  to  which  it  is  to  be  put,  but  even  texture  and 
comparatively  fine  grain  are  essentials.  A  small  amount 
of  clayey  matter  adds  to  the  fineness  of  grinding,  but  an 
excess  lowers  the  abrasive  efficiency  of  the  stone.  In  the 
schists  used,  abrasive  action  is  due  to  the  grains  of  quartz, 
or  sometimes  garnet,  which  are  embedded  among  the  fine- 
grained scales  of  mica. 

Rocks  suitable  for  whetstone  manufacture  are  found  in 
many  states,  especially  east  of  the  Mississippi  (2,  3),  but,  on 
account  of  keen  competition  and  limited  demand,  only  the 
better  grades  from  the  best-located  deposits  are  employed. 
Most  of  the  supply  is  therefore  obtained  from  a  few  states, 
especially  Arkansas,  Indiana,  Ohio,  New  York,  Vermont, 
and  New  Hampshire. 

Among  the  whetstones  quarried  in  the  United  States,  the  Hindostan 
or  Orange  stone  of  Indiana  and  the  Deerlick  oilstone  of  Ohio  are  much 
used  for  oilstones.  Scythestones  are  made  from  schistose  rock  in  Graf- 
ton  County,  New  Hampshire,  and  Orleans  County,  Vermont. 

The  novaculite,  quarried  in  Garland  and  Saline  counties, 
Arkansas  (10),  represents  a  unique  type,  much  prized  for 
high-grade  oilstones  for  sharpening  small  tools,  and  in 
demand  both  at  home  and  abroad.  It  is  an  extremely  fine 
grained  sandstone  made  up  of  finely  fragmental  quartz 
grains,  visible  under  the  microscope.  The  rock  is  chertlike 
in  superficial  appearance  and  has  a  conchoidal  fracture. 
While  the  deposits,  which  are  stratified,  have  a  total  thick- 
ness of  over  500  feet,  the  commercial  novaculite  is  found 


ABRASIVES  161 

only  in  .thin  beds  varying  from  a  few  inches  to  15  feet  in 
thickness.  The  beds  have  a  steep  dip,  and  are  cut  by 
several  series  of  joints,  which  greatly  interfere  with  the 
extraction  of  large  blocks,  and  sometimes  even  with  small 
ones.  There  are  also  structural  irregularities  and  almost 
invisible  flaws,  so  that  much  waste  is  caused  in  quarrying 
the  rock.  The  rock  has  been  variously  regarded  as  a  meta- 
morphosed chert,  a  siliceous  silt,  or  a  silicified  limestone. 

Buhrstones  and  Millstones  (2,  3)  are  stones  of  large  diame- 
ter used  for  grinding  cereals,  paint  ores,  cement  rock,  barite, 
fertilizers,  etc.  The  American  stones  are  either  coarse  sand- 
stone or  quartz  conglomerate,  and  are  quarried  at  several 
points  along  the  eastern  side  of  the  Appalachian  Mountains 
from  New  York  to  North  Carolina.  The  most  important 
beds  are  in  the  Oneida  conglomerate,  which  is  quarried  in 
the  Shawangunk  Mountains  of  eastern  New  York  and  far- 
ther south  in  Pennsylvania.  Some  is  also  quarried  in 
North  Carolina. 

Many  buhrstones  are  imported  from  France,  Belgium,  and  Germany. 
Those  from  the  first  two  localities  are  hard,  cellular  rocks,  consisting 
of  a  mixture  of  fine  quartz  particles  and  calcareous  material ;  but  the 
German  buhrstone  is  basaltic  lava. 

Pumice  and  Volcanic  Ash. — The  term  "pumice,"  as  used 
in  the  geological  sense,  refers  to  the  light  spongy  pieces  of 
lava,  whose  peculiar  texture  is  due  to  the  rapid  and  violent 
escape  of  steam  from  the  molten  lava.  It  is  put  on  the 
market  either  in  lump  form,  or  ground  to  powder,  or  in 
compressed  cakes  of  the  ground-up  material.  In  the  com- 
mercial sense  the  term  "pumice"  includes  volcanic  ash  as 
well  as  true  pumice. 


162          ECONOMIC   GEOLOGY   OF   THE   UNITED   STATES 

Most  of  the  pumice  used  in  the  United  States  is  obtained  from  the 
island  of  Lipari,  north  of  Sicily.  The  stone,  after  being  freed  from  the 
volcanic  ash  with  which  it  is  mixed,  is  sorted  according  to  color,  weight, 
and  size,  before  it  is  shipped  to  market. 

Deposits  of  volcanic  ash  are  abundant  in  many  western 
states,  for  example  in  Nebraska  (12)  and  Utah  (13),  but 
owing  to  inaccessibility  these  materials  cannot  compete  with 
Lipari  pumice,  which  is  imported  as  ballast,  and  sells  in  its 
prepared  form  for  2  to  2|  cents  per  pound. 

Infusorial  Earth  and  Tripoli.  —  These  include  all  porous 
siliceous  earths,  composed  of  organic  fragments,  such  as 
infusoria  or  diatom  tests,  which  have  accumulated  either 
on  the  ocean  bottom  or  in  ponds.  Such  deposits  are  quite 
common  in  the  coastal  plain  area  of  Maryland,  Virginia  (8), 
Georgia  and  Alabama,  where  they  form  beds  several  feet  in 
thickness,  generally  interstratified  with  the  Tertiary  sands 
and  clays.  In  New  England  and  New  York  (7)  infusorial 
earth  is  frequently  found  in  swamps  formed  by  the  filling  of 
ponds.  A  deposit  of  tripoli  worked  near  Carthage,  Missouri 
(9),  differs  from  those  mentioned  above  in  being  the  re- 
sidual silica  left  by  the  leaching  of  an  impure  limestone. 
It  makes  an  excellent  substitute  for  infusorial  earth  as  an 
abrasive.  Infusorial  earth  is  known  in  other  parts  of  the 
country,  for  example,  Nevada  and  California,  but  is  worked 
only  to  a  small  extent. 

The  largest  and  best-known  deposits  of  infusorial  earth  are  in  north- 
ern Germany,  where  it  is  found  from  15  to  18  feet  below  the  surface,  in 
a  bed  varying  from  18  to  45  feet  in  thickness.  This  is  exported  to  all 
parts  of  the  world. 

Infusorial  earth  and  tripoli  are  used  chiefly  for  polishing 
powders  and  scouring  soaps.  The  porous  character  of 


ABRASIVES  163 

infusorial  earth  also  renders  it  valuable  as  an  absorbent  for 
nitroglycerine.  As  a  nonconductor  of  heat  it  is  of  value  for 
steam  boiler  packing,  for  wrapping  steam  pipes,  and  for  fire- 
proof cement.  The  tripoli  of  Missouri  is  used  for  water  filters. 

Crystalline  Quartz  (3).  —  Much  of  the  vein  quartz  quarried 
in  the  United  States  is  pulverized  and  put  on  the  market 
under  the  name  of  tripoli.  Considerable  quartz  sand  is  used 
by  stone  cutters  as  an  abrasive  in  sawing  stone,  and  a  small 
quantity  is  employed  in  making  sandpaper. 

Garnet  (3) .  —  Although  this  is  a  common  mineral  in  many 
metamorphic  rocks,  and  of  some  value  as  an  abrasive,  it  is 
produced  at  but  few  localities.  Most  of  the  supply  comes 
from  North  Carolina,  but  some  is  obtained  in  New  York, 
Connecticut,  and  Tennessee.  It  is  used  in  the  manufacture 
of  garnet  paper,  and  sometimes  as  a  substitute  for  corundum 
in  the  manufacture  of  emery  wheels,  for,  although  softer,  it 
possesses  the  advantage  of  having  a  splintery  fracture,  which 
prevents  it  from  wearing  smooth.  The  price  varies  from  $20 
to  160  per  ton  when  cleaned  for  the  market. 

Corundum  and  Emery  (4,  5,  6).  —  Corundum  (A12O3)  is, 
next  to  diamond,  the  hardest  of  the  natural  abrasives  known, 
having  a  hardness  of  9.  It  varies  slightly  in  hardness,  and 
also  in  chemical  composition,  being  rarely  pure  alumina ;  it 
also  shows  variable  behavior  when  heated,  some  forms 
crumbling  when  exposed  to  a  high  temperature.  Such 
kinds  are  worthless  for  the  manufacture  of  emery  wheels, 
since  it  is  necessary  to  fire  these  in  order  to  fuse  the  clay 
cement  used  in  their  manufacture.  Emery  is  a  mechanical 
mixture  of  corundum  and  magnetite  or  hematite,  and  is 
much  more  abundant  than  corundum.  Its  efficiency  as  an 


164 


ECONOMIC  GEOLOGY  OF  THE  UNITED  STATES 


abrasive  depends  on  the  percentage  of   corundum  which  it 
contains. 

Most  of  the  commercially  valuable  deposits  of  corundum 
have  been  found  in  the  eastern  United  States,  in  a  belt  of 
basic  magnesian  rocks,  extending  from  Massachusetts  to 
Alabama.  These  rocks  reach  their  greatest  development 
in  North  Carolina  (Fig.  31)  and  Georgia,  and  most  of  the 
corundum  is  found  there,  in  veins  on  the  border  of  a  peri- 
dotite  mass  which  has  been  intruded  into  the  gneiss.  It 

is  believed  that 
the  corundum, 
which  was  one 
of  the  earliest 
minerals  to  crys- 
tallize out  from 
the  cooling  peri- 
dotite,  was  con- 
centrated around 
the  borders  of 
the  mass  by  con- 
vection currents. 
This  zone  of  co- 
rundum sent  off 
tongues  toward  the  interior  of  the  mass,  and  now  that  erosion 
has  removed  the  main  zone  of  corundum,  these  tongues  remain 
as  apparently  separate  veins  within  the  peridotite  (Fig.  32). 
The  most  important  emery  deposit  is  that  at  Chester, 
Massachusetts ;  but  some  is  also  worked  near  Peekskill, 
New  York.  The  emery  of  Chester  occurs  in  a  local  widen- 
ing of  a  belt  of  amphibolite  schists,  and  forms  a  vein 
traceable  for  nearly  five  miles.  The  emery-bearing  vein 


FIG.  32.  —  Section  showing  occurrence  of  corundum 
around  border  of  dunite  mass.  After  Pratt,  U.  S. 
Geol.  Surv.,  Bull.  180:  16,  1901. 


ABRASIVES 


165 


varies  in  width  from  a  few  feet  up  to  10  or  12  feet,  while 
the  emery  streak  in  it  averages  about  6  feet,  it  being 
bordered  on  both  sides  by  chlorite  seams.  The  emery  is 
in  pockets,  but  these  are  traceable  by  a  small  vein  of  chlorite. 
After  mining,  both  corundum  and  emery  need  to  be  cleaned 
and  concentrated  by  special  mechanical  processes.  The 
chief  use  of  this  material  is  as  an  abrasive,  and  for  this 
purpose  it  is  used  in  the  form  of  wheels  and  blocks,  emery 
paper,  and  powder. 

Artificial  Abrasives. —  Several  artificial  abrasives  are  now  much  manu- 
factured. Prominent  among  these  is  Carborundum,  which  is  produced 
by  fusion  in  the  electric  furnace  of  a  mixture  of  silica,  coke,  and  saw- 
dust ;  the  reaction  being  SiO2  +  3  C  =  CSi  +  2  CO.  The  sawdust  is 
added  to  give  porosity  to  the  mixture. 

Artificial  corundum  or  alundum,  whose  introduction  is  of  more  recent 
date,  is  made  by  fusing  bauxite  in  the  electric  furnace.  It  is  put  on  the 
market  in  the  form  of  wheels,  while  carborundum  is  either  made  into 
wheels  or  sold  in  powdered  form. 

Production  of  Abrasives.  —  The  value  of  the  abrasives  pro- 
duced in  the  United  States  during  the  last  three  years,  together 
with  the  imports  and  artificial  abrasives,  was  as  follows :  — 


KIND  OF  ABRASIVES 

1901 

1902 

1903 

Oilstones  and  scythestones     .     . 
Grindstones      

$158,300 
580,703 

$221,762 
667,431 

$366,857 
721,446 

Buhrstones  and  millstones     .     . 

57,179 

59,808 
2,750 

52,552 
2,665 

Infusorial  earth  and  tripoli    .     . 
Crystalline  quartz     

52,950 
41,500 

53,224 
84,335 

76,273 
76,908 

158  100 

\y>  820 

132,500 

Corundum  and  emery   .... 

146,040 

104,605 

64,102 

Total  .    

$1,194,772 
383  386 

$1,326,755 
390  °45 

$1,493,303 
493,815 

Imports  

490,712 

426,736 

621,585 

Grand  total    

$2,068,870 

$2,143,736 

$2,608,603 

166          ECONOMIC   GEOLOGY   OF   THE   UNITED   STATES 


REFERENCES  ON  ABRASIVES 

GENERAL.  1.  King,  Ga.  Geol.  Surv.,  Bull.  2 : 119,  1894.  2.  Pratt,  U.  S. 
Geol.  Surv.,  Min.  Res.,  1900:  787,  1901.  3.  Pratt,  Mineral  Census, 
1902,  Mines  and  Quarries:  876,  1905.  — CORUNDUM  AND  EMERY: 
4.  Eckel,  Mineral  Industry,  IX :  15,  1901.  (N.  Y.  emery.)  5.  King, 
Ga.  Geol.  Surv.,  Bull.  2  :  73,  1894.  (Georgia  corundum.)  6.  Pratt, 
U.  S.  Geol.  Surv.,  Bull.  180,  1901.  (U.  S.  occurrence,  mining  and 
concentration.)  —  TRIPOLI  AND  DIATOMACEOUS  EARTH  :  7.  Cox, 
N.  Y.  Acad.  Sci.,  Trans.  XII :  219,  1893,  and  XIII :  98,  1894.  (Diat. 
earth,  N.Y.)  8.  Michels,  Science,  1 :  222, 1880.  (Va.)  9.  Quimby, 
Mineral  Industry,  VI:  17,  1898.  (Mo.)  —  WHETSTONES,  GRIND- 
STONES, AND  MILLSTONES:  10.  Griswold,  Ark.  Geol.  Surv.,  Ann. 
Kept.  1890,  III,  1892.  (Ark.  novaculite.)  11.  Kindle,  Ind.  Dept. 
Geol.  and  Nat.  Res.,  20th  Ann.  Rep. :  329,  1896.  (Ind.)  — PUMICE 
AND  VOLCANIC  ASH:  12.  Barbour,  Neb.  Geol.  Survey,  I:  214,  1903. 
13.  Merrill,  Non-Metallic  Minerals :  398,  N.  Y.,  1904. 


CHAPTER  X 
MINOR  MINERALS  — ASBESTOS 

Asbestos  Minerals.  —  Two  different  minerals  are  mined 
and  sold  under  this  name,  one  a  variety  of  amphibole,  the 
other  a  fibrous  variety  of  serpentine  known  as  chrysotile. 
The  first,  which  forms  pockets  or  veins  in  gneissic  or  schis- 
tose rocks,  is  white,  gray,  or  greenish  white  in  color.  Chryso- 
tile usually  occurs  in  seams  of  varying  width  in  serpentine 
rocks  (Fig.  33),  its  color  being  greenish  white,  green,  or 
yellow,  and  its  luster  silky. 

In  both  forms  of  asbestos  the  fibers  are  easily  separated, 
but  the  amphibole  variety  often  contains  gritty  impurities 
which  are  difficult  to  remove.  The  fibers  of  chrysotile  are 
shorter  than  those  of  the  amphibole  asbestos,  rarely  exceed- 
ing 2^  inches  in  length,  but  they  have  greater  strength. 
Since  the  amphibole  asbestos  can  be  mined  more  easily,  it 
is  cheaper  than  the  chrysotile  variety,  which,  nevertheless, 
is  in  greater  demand  because  more  constant  in  character  and 
suited  to  more  uses.  The  two  varieties  are  equal  in  value 
as  nonconductors  of  heat. 

Distribution.  —  Amphibole  asbestos  is  found  at  a  number 
of  localities  in  the  crystalline  belt  of  the  Appalachians,  but 
at  present  Sail  Mountain  in  White  County,  Georgia,  is  the 
only  producer,  although  promising  deposits  are  known  in 
Polk  County,  North  Carolina,  and  Bedford  County,  Virginia, 
and  are  worked  occasionally. 

167 


168 


ECONOMIC   GEOLOGY   OF   THE   UNITED   STATES 


The  limited  supply  of  chrysotile  asbestos  has  naturally 
stimulated  prospecting,  and  deposits  of  promise  have  been 
found  in  Vermont  (4),  Wyoming,  California,  Montana  (8), 

and  Arizona  (9). 
The  Vermont  de- 
posits, discovered 
in  1900,  occur  in 
Lamoille  and  Or- 
leans County,  oc- 
cupying a  rather 
limited  area  in  a 
large  serpentine 
belt  (4).  Two 
types  of  chryso- 
tile are  found,  one 
forming  branch- 
ing veins  similar 
in  character  and 
quality  to  the 
Canadian  fiber, 
the  other,  of  inferior  quality,  occurring  as  short  fibers  on 
slickensided  surfaces. 

The  main  supply  of  chrysotile  used  in  the  United  States 
is  obtained  from  Black  Lake  and  Thetford,  Quebec.  The 
serpentine  is  blasted  out  and  the  lumps  bearing  chrysotile 
separated  from  the  barren  rock  by  hand  picking.  These 
are  crushed  and  screened  and  the  fibres  then  separated  from 
the  rock  by  air  currents.  It  is  stated  that  100  tons  of  rock 
yields  two  tons  of  commercial  asbestos  (5,  8). 

There  has  been  some  difficulty  in  explaining  satisfactorily 
the  origin  of  the  chrysotile  veins  in  serpentine,  for  we  have 


FIG.  33.  —  Asbestos  vein  in  serpentine.    Photo,  by  G.  P. 
Merrill. 


MINOR  MINERALS  169 

here  two  quite  different  forms  of  the  same  mineral.  Pratt, 
in  attempting  to  explain  the  origin  of  the  vein  filling, 
believes  that  the  fissures  represent  contraction  cracks  formed 
around  the  edge  of  the  serpentine  mass  while  cooling,  and 
which  were  then  filled  by  aqueous  solutions  from  which  the 
chrysotile  crystallized.  Merrill,  on  the  other  hand,  believes 
the  fissures  to  have  been  caused  by  shrinkage  incident  to  a 
partial  dehydration  of  the  rocks  and  subsequent  filling  by 
crystallization  extending  from  the  walls  inward  (6). 

Uses.  —  Asbestos  is  used  in  fireproof  paints,  boiler  cover- 
ing, for  packing  in  fire  safes,  and  for  other  purposes  where 
non-conductivity  of  heat  is  required.  Chrysotile  is  also 
used  in  making  fireproof  rope,  felt,  tubes,  cloth,  boards, 
blocks,  and  other  objects.  Asbestic  is  a  name  given  to 
short-fibered  chrysotile  mixed  with  serpentine. 

Production  of  Asbestos.  —  The  production  of  asbestos  for 
the  last  three  years  was  as  follows  :  — 


YEAR 

SHORT  TONS 

VALUE 

1901 

747 

f  13,498 

1902 

1005 

16,200 

1903 

887 

16,760 

The  imports  in  1903  were  valued  at  $689,327. 

REFERENCES  ON  ASBESTOS 

1.  Ells,  Amer.  Inst.  Min.  Engrs.,  XVIII:  320,  1890.  (Ontario.) 
2.  Jones,  Asbestos  and  Asbestic  :  Their  Properties,  Occurrence,  and 
Use  (London),  1897.  3.  Pratt,  U.  S.  Geol.  Surv.,  Min.  Res.,  1904. 

4.  Kemp,  U.  S.  Geol.  Surv.,  Min.  Res.,  1900:   862,  1901.     (Vt.) 

5.  Merrill,  National  Museum  Guide  to  Study  of  Non-metallic  Min- 
erals, 296:  1901.      (General.)    6.  Merrill,  Geol.   Soc.   Amer.,  Bull. 
XVI,  1905.     (Origin.)    7.    Pratt,  U.  S.  Geol.  Surv.,  Min.  Res.,  1901 : 
887,  1902.     8.  Pratt,  Mineral  Census,  1902,  Report  on  Mines  and 
Quarries :  973,  1904. 


170          ECONOMIC   GEOLOGY   OF   THE   UNITED   STATES 

BARITE 

Barite,  the  sulphate  of  barium,  is  abundant  at  many 
localities,  and  in  a  few  places  in  sufficient  quantity  to  be 
of  commercial  value.  Its  usual  mode  of  occurrence  is  as  a 
series  of  pockets  or  lenses,  which  conform  to  the  dip  of  the 
inclosing  rock,  often  limestones.  Galena  is  a  common  asso- 
ciate. Deposits  of  commercial  value  are  found  in  Connecti- 
cut, North  Carolina,  Tennessee,  Virginia,  and  Missouri  (2). 
At  Evington,  Virginia  (3),  where  the  mines  have  been  worked 
since  1874,  the  barite  forms  lenticular  pockets  in  limestone. 
The  barite-bearing  stratum  has  a  total  length  of  about  4 
miles  and  a  width  of  100  to  200  feet  or  more.  The  pockets 
dip  from  20°  to  30°  to  the  east,  and  are  sometimes  separate 
or  may  be  connected  by  thin  stringers  of  barite.  Limestone 
is  associated  with  the  Tennessee  and  Missouri  deposits,  but 
in  North  Carolina  barite  lenses  3  to  6  feet  thick  occur  in  a 
decomposed  schist. 

The  following  analysis  of  barite  from  Fulton  County,  Pennsylvania, 
shows  the  impurities  which  it  may  contain :  BaSO4,  95.22 ;  Fe2O3,  A12O3, 
.38;  MnO2,  .05;  CaO,  .59;  MgO,  .18;  CO2,  .65;  H2O,  .23;  SiO2,  2.45. 

Uses.  —  Barite,  which  is  pulverized,  and  sometimes  puri- 
fied by  washing,  is  used  in  the  manufacture  of  paper,  rubber, 
paints,  and  for  coating  canvas  ham  sacks.  It  is  also  used  in 
pottery  glazes  and  in  the  manufacture  of  barium  hydroxide. 
Its  white  color  and  great  weight  (sp.  gr.  4.3)  make  it  of 
value  as  an  adulterant  of  white  lead.  Lithophone  paint  is  a 
mixture  of  barium  sulphate  (68  per  cent),  zinc  oxide  (7.28 
per  cent),  and  zinc  sulphide  (24.85  per  cent). 

Production.  —  The  production  of  barite  for  several  years 
has  been  as  follows :  — 


MINOR   MINERALS 


171 


PRODUCTION  OF  CRUDE  BARITE  IN  THE  UNITED  STATES  FROM 
1901  TO  1903 


1901 

1902 

1903 

Quantity 
Short 

Value 

Quantity 
Short 

Value 

Quantity 
Short 

Value 

tons 

tons 

tons 

Missouri 

20,950 

$73,814 

31,334 

$104,677 

23,178 

$77,712 

North  Carolina 

7,390(6) 

22,615 

14,679 

44,130 

6,835 

21,347 

Tennessee   .     . 

10,460 

30,155 

3,255 

14,647 

14,684(a) 

32,691 

Virginia      .     . 
Total  .     .     . 

20,950 

31,260 

12,400 

39,700 

5,700 

20,400 

49,070 

$157,844 

61,668 

$203,154 

50,397 

$152,150 

(a)  Includes  the  small  production  of  Kentucky. 
(6)  Includes  the  small  production  of  Georgia. 

The  imports  of  crude  barites  in  1903  amounted  to  7105 
pounds,  valued  at  $22,777,  while  those  of  manufactured 
barites  were  5716  pounds,  valued  at  $48,726. 

REFERENCES  ON  BARITE 

1.  McCallie,  Ala.  Indus,  and  Sci.  Soc.,  Proc.  V :  25, 1895.  (Ala.)  2.  Eng. 
and  Min.  Jour.,  LXXIII :  762,  1902.  (Mo.)  3.  Pratt,  U.  S.  Geol. 
Surv.,  Min.  Res.,  1901 :  915,  1902.  (General.) 


FLUORSPAR 

Fluorspar  or  fluorite  (CaF2),  a  widely  distributed  mineral 
of  variable  colors,  including  white,  green,  and  purple,  is  com- 
monly found  in  veins,  including  limestones,  sandstones,  slates, 
and  gneisses,  but  seems  to  favor  metamorphic  rocks.  It  is  not 
an  uncommon  constituent  of  many  igneous  rocks,  and  enters 
into  the  composition  of  some  minerals,  such  as  apatite,  cer- 


172          ECONOMIC   GEOLOGY   OP   THE   UNITED   STATES 

tain  micas  and  topaz.  Fluorite  has  also  been  observed  in  con- 
nection with  some  volcanic  outbursts.  (See  Cripple  Creek, 
under  Gold.)  Calcite  and  galena  are  sometimes  found  in 
the  same  vein.  Fluorite  is  also  noted,  though  rarely  in 
economic  quantities,  in  the  gangue  of  many  metallic  minerals, 
especially  lead. 

Distribution  in  United  States.— In  the  United  States  fluorite 
is  found  at  a  number  of  points  in  the  Piedmont  and  Ap- 
palachian areas  from  Maine  to  Virginia,  and  is  likewise  noted 
in  small  amounts  in  many  metalliferous  veins  of  the  West, 
but  it  is  rarely  found  in  the  Mississippi  Valley.  In  unaltered 
limestone  it  is  exceedingly  rare,  and  the  only  commercially 
important  deposits  found  in  this  kind  of  rock  are  in  areas  of 
igneous  intrusions. 

Until  1898  the  mines  of  Hardin  and  Pope  counties,  Illi- 
nois, were  the  only  domestic  source  (1),  and  this  area  con- 
tinues to  be  the  most  important  producer.  There  the  deposits 
fill  fault  fissures  in  Lower  Carboniferous  limestone  or  sand- 
stone. Dikes  of  mica  peridotite  and  lamprophyre  also  occur 
in  the  district,  but  not  in  contact  with  the  veins.  These 
latter  in  some  places  attain  a  width  of  45  feet  and  a  proven 
depth  of  200  feet.  This  great  width  is  due  partly  to  enlarge- 
ment of  the  fissure  by  solution,  and  partly  to  a  replacement 
of  the  limestone  walls.  In  the  limestone  footwall,  the  fluor- 
spar sometimes  forms  a  solid  mass  from  2  to  12  feet  thick,  but 
that  on  the  hanging  wall  is  less  pure.  The  vein  filling  is 
chiefly  fluorite  and  calcite,  while  associated  with  these  are 
smaller  amounts  of  galena,  sphalerite,  and  occasionally  pyrite 
or  chalcopyrite.  It  is  significant  that  the  galena  is  slightly 
argentiferous. 


MINOR   MINERALS  173 

The  origin  of  the  fluorite  is  somewhat  doubtful,  but 
Bain  (1)  believes  that  it  has  probably  been  derived  from 
heated  waters  of  either  meteoric  or  magmatic  origin  which 
leached  the  mineral  from  some  large  mass  of  low-lying 
igneous  rocks  of  which  the  dikes  are  offshoots.  These 
heated  ascending  solutions  are  thought  to  have  carried 
fluosilicates  of  zinc,  lead,  copper,  iron,  barium,  and  calcium. 
The  dissolved  compounds  were  probably  broken  up  by  cold 
descending  waters,  which  possibly  also  furnished  the  sulphur 
to  combine  with  the  metals. 

Fluorspar  deposits  are  also  known  in  Kentucky  (5),  Ten- 
nessee (6),  and  Arizona  (6),  in  the  latter  state  occurring  as  a 
common  gangue  mineral  of  the  metalliferous  veins  in  Yum  a 
County. 

Uses.  —  Fluorspar  was  formerly  used  chiefly  for  making 
hydrofluoric  acid,  but  not  more  than  5  to  10  per  cent  of  the 
domestic  product  is  now  employed  for  this  purpose,  while  in- 
creasing quantities  are  sold  for  the  manufacture  of  opalescent 
glass.  The  greatest  demand  for  it,  however,  is  as  a  flux  in 
iron  manufacture,  since  it  saves  from  3  to  5  per  cent  more  iron 
than  limestone  flux,  reduces  the  sulphur  and  phosphorus 
contents,  and  increases  the  tensile  strength  of  the  metal. 
On  account  of  its  valuable  reducing  properties,  it  is  also 
used  in  making  spiegeleisen,  in  foundry  work,  and  in  cupola 
furnaces.  One  objection  to  the  more  widespread  use  of 
fluorspar  as  a  flux  has  been  its  high  cost  as  compared  with 
limestone. 

Fluorspar  is  divided  into  6  grades  for  the  market,  the  first- 
grade  lump  bringing  $14.40  per  ton  in  1903. 

The  production  of  fluorspar  for  1903  was  as  follows  :  — 


174  ECONOMIC    GEOLOGY   OF   THE    UNITED   STATES 

PRODUCTION  OF  FLUORSPAR  IN  UNITED  STATES  IN  1903 


STATE 

QUANTITY 
SHORT  TONS 

VALUE 

Arizona  and  Tennessee  

275 

$2037 

30885 

153  960 

Illinois 

11  413 

57  620 

Total 

42  523 

<$213  617 

REFERENCES  ON  FLUORSPAR 

1.  Bain,  U.  S.  Geol.  Surv.,  Bull.  255,  1905.  (111.)  2.  Burk,  Min.  Ind., 
IX :  293, 1901.  (Ky.)  3.  Emmons,  Amer.  Inst.  Min.  Engrs.,  Trans. 
XXI:  51,  1893.  (111.)  4.  Min.  Indus.,  IX:  203,  1901.  5.  Fohs, 
Min.  Ind.,  XII:  131,  1904.  (Ky.-Ill.)  6.  Pratt,  U.  S.  Geol.  Surv., 
Min.  Res.  1901 :  879,  1902.  (Gen.) 


FULLER'S  EARTH 

Fuller's  earth  is  a  term  applied  to  a  claylike  mate- 
rial which  has  the  property  of  absorbing  greasy  sub- 
stances. It  was  first  used  for  fulling  cloth  or  fur  and 
hence  the  name,  but  in  more  recent  years  it  has  been  found 
of  great  value  for  the  clarification  of  mineral  and  vege- 
table oils,  being  used  with  the  former  as  a  substitute  for 
charcoal. 

While  fuller's  earth  resembles  clay  superficially,  it  usually 
differs  from  it  in  having  lower  plasticity,  and  a  higher  per- 
centage of  combined  water  as  compared  with  the  alumina 
contents.  It  is  often,  though  not  invariably,  high  in  mag- 
nesia. In  color,  fracture,  and  texture,  it  varies  considerably, 
and  the  only  satisfactory  way  of  determining  its  value  is  by 
a  practical  test. 


MINOR   MINERALS 


175 


Fuller's  earth  is  not  confined  to  any  particular  formation, 
but  the  known  deposits  occur  in  sedimentary  rocks  ranging 
from  the  beginning  of  the  Mesozoic  up  to  the  Pleistocene. 
In  Gadsden  County,  Florida,  and  in  Decatur  County, 
Georgia  (1,  3),  it  is  obtained  from  the  Upper  Oligocene  of  the 
Tertiary,  the  former  locality  being  the  most  important  in  the 
country.  The  earth  from  this  region  is  used  for  bleaching 
mineral  oils. 

Earth  of  at  least  fair  quality  has  been  found  at  other  localities  in 
the  southern  coastal  plain  district.  Small  quantities  of  fuller's  earth 
are  also  produced  in  Arkansas,  eastern  Colorado,  and  central  New  York 
(2).  The  last-mentioned  occurrence  has  been  used  for  cleansing  cloth  and 
also  in  the  manufacture  of  soap.  It  is  known  to  occur  in  Nebraska, 
South  Dakota  (2),  and  Alabama. 

Before  the  development  of  the  Florida  deposits,  in  1893,  much  fuller's 
earth  was  imported  from  England,  and  even  now  a  considerable  amount 
is  imported  for  use  by  the  refiners  of  cotton-seed  oil,  since  it  bleaches 
better  than  most  of  the  American  earth. 

The  following  analyses  indicate  the  composition  of  Ameri- 
can fuller's  earth,  and  to  these  are  added  some  analyses  of 
the  English  material,  for  purposes  of  comparison,  although 
chemical  composition  is  of  little  value  as  a  guide  to  the 
quality  of  the  material. 


SiO2 

A1208 

Fe208 

CaO 

MgO 

H20 

Na2o|  K20 

Moist. 

Quincy,  Fla.  .     .     . 

62.83 

10.35 

2.45 

2.43 

3.12 

7.72 

.20  1  .74 

6.41 

Decatur  Co.,  Ga.    . 

67.46 

10.08 

2.49 

3.14 

4.09 

5.61 

<  .  ' 

6.41 

Fairburn,  S.  D.  .     . 

58.72 

16.90 

4.00 

4.06 

2.56 

8.10 

2.11 

2.20 

Sumter,  S.  C.     .     . 

74.20 

10.10 

1.80 

1.90 

2.10 

5.70 

1.60 

2.50 

Yellow  earth. 

Woburn  Sands,  Eng. 

47.10 

16.27 

10.66 

2.63 

3.15 

5.73 

15.12 

176          ECONOMIC    GEOLOGY    OF   THE   UNITED   STATES 

Production  of  Fuller's  Earth.  —  The  domestic  output  has 
never  been  large,  and  much  is  still  imported  from  England. 

PRODUCTION  OF  FULLER'S  EARTH  IN  UNITED  STATES 
FROM  1901  TO  1903 


SHORT  TONS 

VALUE 

1901 

14  112 

$96  835 

1902      .  .        .    ... 

11  492 

98144 

1903  

20,693 

190,277 

REFERENCES  ON  FULLER'S  EARTH 

1.  Ries,  U.  S.  Geol.  Surv.,  17th  Ann.  Kept.,  Ft.  Ill  (cont.) :  876,  1896. 

2.  Ries,  Amer.  Inst.  Min.  Engrs.,  Trans.  XXVII:  333, 1898.  (S.  Dak.) 

3.  Vaughan,  U.  S.  Geol.  Surv.,  Bull.  213  :  392,  1903.     (Fla.  and  Ga.) 


GLASS  SAND 

Glass  sand  is  obtained  from  quartzose  sands,  sandstones,  or 
quartzites,  usually  having  at  least  98  per  cent  of  silica  and 
a  very  low  percentage  of  iron  oxide,  as  seen  from  the  analyses 
given  below.  When  sand  is  employed,  it  is  sometimes 
necessary  to  put  it  through  a  washing  process  in  order  to 
separate  the  impurities,  while  in  the  case  of  quartzite  or  sand- 
stone a  preliminary  crushing  and  screening  are  necessary. 
Clay  is  undesirable  since  it  tends  to  cloud  the  glass,  while 
iron  oxide  imparts  an  undesirable  color;  but  this  may  be 
counteracted  to  some  extent  by  the  addition  of  arsenic. 

Sands  for  glass  making  are  sometimes  obtained  from 
Pleistocene  deposits,  but  those  from  the  Tertiary  and 
Cretaceous  formations  are  of  better  quality.  Quartz  rock 
(sandstone  and  quartzite)  is  found  at  various  localities  in 
the  Paleozoic  strata. 


MINOR   MINERALS 


177 


Much  sand  is  obtained  from  Silurian  sandstones  in  La  Salle 
and  Randall  counties,  Illinois  (5),  for  use  in  the  plate  glass 
works  at  Chicago.  In  New  Jersey  there  are  extensive  pits 
in  the  Tertiary,  around  Bridgeton  (4),  the  material  being 
used  by  the  glass  works  of  southern  New  Jersey  and  south- 
eastern Pennsylvania.  Large  pits  are  also  opened  in  the 
Raritan  formation  of  the  Cretaceous  along  the  Severn  River  in 
Maryland  (5).  Of  the  quartz  rocks,  the  Cambrian  quartzites 
in  Berkshire  County,  Massachusetts  (5),  the  Oriskany  sand- 
stone of  West  Virginia,  and  those  of  Pennsylvania  (7)  are  all 
of  importance.  In  Iowa  the  St.  Peters  sandstone  is  used  (2). 

The  following  analyses  taken  from  several  American  lo- 
calities will  serve  to  show  the  composition  of  the  materials 
employed :  — 


LOCALITY 

SiO2 

A1208 

Fe208 

CaO 

MgO 

MISCEL- 
LANEOUS 

GEOLOGICAL 
AGE 

Ottawa,  111.      .     . 

99.45 

.30 

.13 

Tr 

Silurian 

Hanover,  N.  J.     . 

97.705 

.755 

.150 

.955 

.442 

Tertiary 

Berkeley  Springs, 

Moist. 

W.  Va.    .     .     . 

99.37 

.33 

.04 

.17 

Oriskany 

Loss,  etc. 

Columbia,  Pa. 

99.5044 

.1337 

.2998 

.062 

Oriskany 

Cheshire,  Mass.    . 

99.46 

.48 

.06 

Cambrian 

Ignition 

Lewiston,  Pa.  .     . 

98.84 

.17 

.34 

Tr 

Tr 

.23 

Oriskany 

Loss,  etc. 

Clayton,  la.     .     . 

98.85 

.46 

.095 

.21 

.384 

Ordovician 

The  total  production  of  glass  sand  in  1903  is  given  by  the 
United  States  Geological  Survey  as  823,044  short  tons  valued 
at  8855,828,  and  came  from  twelve  states.  It  is  doubtful, 
however,  whether  all  this  was  used  in  glass  manufacture. 
Ohio  is  credited  with  being  the  largest  producer  and  Illinois 
second. 


178          ECONOMIC   GEOLOGY   OF   THE   UNITED   STATES 


ON  GLASS  SAND 

1.  Broadhead,  Mo.  Geol.  Surv.,  1872:  289,  1873.  (Mo.)  2.  Calvin, 
la.  Geol.  Surv.,  I:  24,  1893.  (la.)  3.  Collett,  Geol.  and  Nat. 
Hist.  Surv.  of  Ind.,  12th  Ann.  Kept. :  22,  1883.  (Ind.)  4.  Cook, 
Geology  of  New  Jersey,  1868  :  690,  1868.  (N.  J.)  5.  Coons,  U.  S. 
Geol.  Surv.,  Min.  Res.,  1902  :  1007;  1903.  (General.)  6.  DeGroot, 
Calif.  State  Min.  Bur.,  9th  Ann.  Kept. :  324, 1890.  (Calif.)  7.  D'ln- 
villiers,  Second  Pa.  Geol.  Surv.,  F,  1878.  (Pa.)  8.  Fuller,  Stone, 
XVIII :  1,  1898.  (General.) 


GRAPHITE 

Graphite,  or  black  lead  as  it  is  often  termed  popularly,  is 
a  form  of  carbon,  and  occurs  in  two  forms,  the  crystalline 
and  amorphous.  The  first  type  is  commonly  found  in  granular 
or  foliated  masses,  while  the  latter  lacks  crystalline  struc- 
ture and  is  often  shaly  in  its  character.  On  this  account 
some  carbonaceous  schists  which  resemble  the  latter  in 
appearance,  but  contain  no  graphite  whatever,  are  put 
on  the  market  under  its  name.  Even  the  best  grades  of 
crystalline  graphite  are,  however,  never  pure  carbon,  as 
the  following  analysis  shows:  — 


C 

ASH 

VOLATILE  MATTER 

Ceylon  graphite    .     .     . 

98.87 

.28 

.90 

Distribution  of  Graphite  in  United  States.  —  Crystalline 
graphite  is  widely  distributed  in  the  United  States,  occur- 
ring in  contact  zones  between  igneous  and  sedimentary 
rocks,  in  metamorphosed  rocks,  etc.,  but  the  known  de- 
posits of  commercial  value  are  few  in  number.  Most  of 
the  domestic  supply  has  been  obtained  from  the  mines 


MINOR   MINERALS  179 

near  Ticonderoga  (3),  Essex  County,  New  York,  where  the 
mineral  occurs  in  a  gray  quartzite,  which  is  interbedded 
with  gametiferous  and  micaceous  gneiss  and  a  quartzite. 
The  rock  contains  about  10  per  cent  graphite,  but  not 
more  than  50  per  cent  of  this  is  saved  in  the  process  of 
extraction  or  concentration.  Crystalline  graphite  is  also 
mined  in  Chester  County,  Pennsylvania,  where  it  forms 
two  layers  from  4  to  6  feet  thick  in  decomposed  mica  schist 
(2,  4).  Deposits  are  also  known  in  Alabama,  Georgia, 
North  Carolina,  New  Hampshire,  and  Montana  (4),  but  none 
of  the  localities  have  been  important  producers.  Amor- 
phous graphite  occurs  in  Rhode  Island  (4)  in  metamor- 
phosed carboniferous  rocks,  and  the  locality  has  attracted 
attention  for  many  years,  but  its  production  has  been  very 
irregular,  due  partly  to  the  fact  that  most  attempts  to 
utilize  it  have  been  unsuccessful.  The  material  is  some- 
what scaly,  but  does  not  as  a  rule  carry  more  than  55'  per 
cent  carbon,  the  balance  being  siliceous  impurities.  That 
produced  in  Michigan  (4)  and  Wisconsin  is  simply  car- 
bonaceous schist,  containing  no  graphite  whatever. 

Most  of  the  graphite  used  in  the  United  States  is  obtained  from 
Ceylon,  where  it  occurs  as  veins  in  granulite  and  associated  with 
feldspar,  rutile,  pyrite,  biotite,  and  calcite.  Weinschenk  believes  these 
deposits  to  have  been  formed  by  the  decomposition  of  vapors  carry- 
ing carbonic  oxide  and  cyanogen  compounds.  Styria,  Bohemia,  and 
Bavaria  are  also  important  foreign  sources  of  supply.  All  of  these 
localities  supply  the  American  market,  but  Ceylon  is  the  most  impor- 
tant source  by  far. 

Uses.  —  On  account  of  its  refractoriness  and  high  heat 
conductivity,  graphite  is  employed  in  the  manufacture  of 
crucibles,  for  which  purpose  it  is  mixed  with  clay  and 


180 


ECONOMIC   GEOLOGY   OF   THE   UNITED   STATES 


some  sand.  In  addition  it  is  employed  for  making  stove 
polish,  foundry  facings,  paint,  lead  pencils,  lubricating 
powder,  glazing,  electrotyping,  steam  piping,  etc. 

Graphite  is  also  made  artificially  from  anthracite  coal, 
but  its  introduction  has  not  seriously  affected  the  market 
for  the  natural  product. 

Crystalline  graphite  is  put  through  a  concentrating  process  before 
shipment  to  market.  This  is  necessary  in  order  to  free  it  from  the 
associated  minerals.  Both  wet  and  dry  methods  of  separation  are 
employed,  while  more  recently  air  separation  has  been  tried  with 
some  success. 


Production  of  Graphite.  —  The  domestic  production  of 
crystalline  graphite  does  not  form  more  than  a  small  pro- 
portion of  the  entire  consumption,  and  has  shown  but  a 
slight  increase,  whereas  the  output  of  amorphous  graphite 
has  shown  great  expansion,  as  can  be  seen  by  the  figures 
given  below. 

PRODUCTION  OF  GRAPHITE  IN  UNITED  STATES  FROM  1901  TO  1903 


1901 

1902 

1903 

Amor- 
phous 

Crystalline 

Value  of 
both 

Amor- 
phous 

Crystalline 

Value  of 
both 

Amor- 
phous 

Crystalline 

Value  of 
both 

Short 
tons 
809 

Lbs. 
3,967,612 

$167,714 

Short 
tons 
4,739 

Lbs. 
3,936,824 

$182,108 

Short 
tons 
16,591 

Lbs. 
4,538,155 

$225,554 

The  exports  in  1903  were  valued  at  $133,651,  while  the 
imports  were  valued  at  $1,207,730.  The  total  domestic 
consumption  for  that  year  was  37,758  short  tons,  valued 
at  $1,598,589. 

The  world's  production  in  1902  is  given  below :  — 


MINOR   MINERALS  181 

WORLD'S  PRODUCTION  OF  GRAPHITE  IN  1902 


METRIC  TONS 

VALUE 

Ceylon    

Austria 

25,593 
29527 

$3,505,455 
368  186 

United  States  

6,085 

182  108 

5023 

41  755 

Italy  . 

9210 

35934 

Canada 

994 

28300 

Mexico    

580 

3  176 

63 

1  900 

France    

150 

1  140 

India  

4,648 

(*) 

Total    

81,873 

$4,167,954 

(&)  Statistics  not  available. 

REFERENCES  ON   GRAPHITE 

1.  Downs,  Iron  Age,  Apr.  19  to  June  14,  1900.  2.  Frazer,  Amer.  Inst. 
Min.  Engrs.,  Trans.  IX :  730,  1881.  (Pa.)  3.  Nason,  N.  Y.  State 
Museum,  Bull.  4:  12,  1888.  (N.  Y.)  4.  See  also  various  volumes 
of  the  Mineral  Industry,  especially  XI :  343, 1903,  and  XII :  183, 1904. 


LITHOGRAPHIC  STONE 

Lithographic  stone  (1, 3)  is  a  very  fine-grained,  homo- 
geneous limestone,  used  for  lithographic  purposes.  It  may 
be  either  pure  lime  carbonate  or  magnesian  limestone,  but  so 
far  as  known  this  difference  in  composition  exerts  no  impor- 
tant influence  on  its  physical  character.  The  two  following 
analyses  will  serve  to  indicate  this  difference  in  composi- 
tion, No.  1  being  the  standard  Bavarian  stone  and  No.  2 
the  Brandenburg,  Kentucky,  rock:  — 

INSOLUBLE  IN  HC1  SOLUBLE  IN  HC1 


SiO,     (AlFe)203       CaO      A1,O, 

1.  1.15        .22        Trace     .23 

2.  3.15        .45          .09       .13 


FeO    MgO      CaO      Na,O    K2O    Moist.    H,O      CO, 

.26      .56    53.80          .07  .23      .69    42.69 

.31    6.75    44.76          .13  .41      .47    43.06 


182          ECONOMIC   GEOLOGY   OF   THE  UNITED   STATES 

The  physical  character  of  the  stone  is  of  prime  impor- 
tance, for  in  order  to  yield  the  best  results  it  should  be 
fine-grained,  homogeneous,  free  from  veins  or  cracks,  of 
just  sufficient  porosity  to  absorb  the  grease  holding  the 
ink,  and  soft  enough  to  permit  its  being  carved  with  the 
engraver's  tool.  Owing  to  these  strict  requirements  but 
few  localities  have  produced  good  stone.  Lithographic 
stone  is  not  confined  to  any  one  geologic  formation,  and 
deposits  have  been  reported  from  many  states  both  east 
and  west.  Some  of  these  appear  to  be  of  inferior  quality, 
while  others  are  too  far  from  railroads.  The  most  prom- 
ising developed  deposit  is  that  found  at  Brandenburg,  Ken- 
tucky (2,  6),  at  which  locality  a  bed  of  blue-gray  stone 
three  feet  thick  is  quarried  and  used  by  some  establish- 
ments in  the  south  and  southwest.  Another  bed  of  good 
quality  has  also  been  described  from  Iowa  (1). 

The  main  source  of  the  world's  supply  is  obtained  from  the  Jurassic 
limestone  of  the  Solenhofen  district  in  Bavaria  (4),  in  which  the  quarries 
have  been  worked  for  a  number  of  years,  but  the  supply  is  said  to  be 
becoming  unsatisfactory  and  unreliable.  The  stones  are  trimmed  at  the 
quarries,  and  sizes  of  22  or  28  by  40  inches  are  in  the  greatest  demand. 
From  these  they  range  up  to  sizes  40  by  60  inches.  The  best  quality 
stones  sell  for  22  cents  per  pound. 

The  domestic  demand  is  not  large,  and  it  is  probable 
that  one  or  two  well-developed  and  well-managed  native 
quarries  could  no  doubt  satisfy  it. 

The  successful  substitution  of  zinc  or  aluminum  plates 
for  certain  classes  of  lithographic  work  is  said  to  have  had 
a  noticeable  influence  on  the  demand  for  lithographic  stone. 
Onyx  has  also,  in  some  cases,  been  found  to  make  a  good 
substitute. 


MINOR  MINERALS  183 

REFERENCES  OW  LITHOGRAPHIC  STOKES 

1.  Hoen,  la.  Geol.  Surv.,  XIII :  339, 1902.  (la.  also  general.)  2.  Kiibel, 
Eng.  and  Min.  Jour.,  LXXII:  668,  1901.  (Ky.)  3.  Kiibel,  Min. 
Resources,  U.  S.  Geol.  Surv.,  1900 :  869,  1901.  (Excellent  general 
article.)  4.  Merrill,  Non-Metallic  Minerals:  146,  1904.  5.  Mo. 
Geol.  Surv.,  Bull.  3 :  38,  1890.  (Mo.)  6.  Ulrich,  Eng.  and  Min. 
Jour.,  LXXIII :  895,  1902.  (Ky.) 

LITHIUM 

The  two  minerals  most  commonly  used  as  a  source  of 
lithium  are  lepidolite  (KLi[Al(OH1F2)]Al(SiO3)3)  and 
spodumene  (LiO2,  A12O3,  4  SiO2).  The  largest  deposits  of 
lepidolite  at  present  known  in  the  United  States  are  found 
near  Pala,  California.  Spodumene  occurs  in  some  quan- 
tities in  the  Black  Hills  of  South  Dakota  and  in  Connecti- 
cut and  Massachusetts,  but  none  of  these  occurrences  have 
yet  been  worked  to  supply  lithium. 

In  the  last  few  years  there  has  been  a  great  demand  for 
lithium  minerals  for  use  in  the  manufacture  of  lithium  car- 
bonate. Since  most  of  this  substance  now  in  use  is  made 
in  Germany,  nearly  all  the  American  mineral  has  been 
shipped  to  that  country.  The  American  supply  of  carbon- 
ate is  imported  from  Germany,  selling  in  New  York  for 
$4.20  a  pound.  The  chief  use  of  lithium  salts  is  in  the 
preparation  of  mineral  waters. 

The  production  of  lithium  minerals  in  the  United  States 
in  1903  amounted  to  1155  short  tons,  valued  at  $23,425. 

MAGNESITE 

This  mineral  (1),  which  is  a  carbonate  of  magnesium  with 
47.6  per  cent  of  magnesia,  usually  occurs  as  a  decomposi- 
tion product  in  the  form  of  irregular  veins  in  serpentine, 
talcose  schists,  or  other  magnesian  rocks.  Its  color  is 


184         ECONOMIC   GEOLOGY   OP  THE   UNITED   STATES 

white  or  yellowish,  and  when  massive  it  resembles  unglazed 
porcelain,  but  is  quite  brittle.  Most  of  the  magnesite  used 
in  the  United  States  is  imported  from  Styria  and  Greece ; 
but  some  is  obtained  in  California  (3),  where  a  commercially 
valuable  deposit  is  known. 

Magnesite  is  employed  in  the  preparation  of  magnesium 
salts  and  in  the  manufacture  of  paint  and  of  paper.  Since 
it  is  a  nonconductor  of  heat,  it  finds  extensive  use  for  this 
purpose ;  in  fact,  its  most  important  use  is  as  a  refractory  lin- 
ing for  open-hearth  furnaces  and  converters  in  the  steel  indus- 
try, and  for  the  brick  lining  of  rotary  Portland  cement  kilns. 

The  domestic  production  is  obtained  entirely  from  Cali- 
fornia, and  has  been  as  follows :  — 

PRODUCTION  OF  MAGNESITE  IN  UNITED  STATES  FROM  1901  TO  1903 


YEAR 

QUANTITY 
SHORT  TONS 

VALUE 

1901                                                .... 

3500 

$10,500 

1902  

2830 

8,490 

1903                                    .         ... 

3744 

10,595 

The  total  value  of  crude  and  calcined  magnesite  imported 
in  1903  was  $461,398. 

REFERENCES  ON  MAGNESITE 

1.  Struthers,  U.  S.  Geol.  Surv.,  Min.  Res.,  1902  :  983, 1903.  2.  Yale,  Eng. 
and  Min.  Jour.,  LXXVIII :  292, 1904.  (Calif.)  3.  Yale,  U.  S.  Geol. 
Surv.,  Min.  Res.,  1903  :  1131,  1904.  (Calif,  and  general.) 

MICA 

There  are  few  minerals  more  widely  distributed  in  crystal- 
line rocks  than  mica,  and  yet  deposits  of  economic  value 
are  rare  because  the  mica  flakes  are  either  too  small,  or  too 


MINOR   MINERALS  185 

intimately  mixed  with  other  minerals  for  profitable  extrac- 
tion. Only  two  of  the  several  known  varieties  of  mica,  mus- 
covite  (H2KAl3Si3O12)  and  phlogopite  (HgKgMgyAl^SiO^, 
are  of  economic  value,  the  former  being  more  valuable  than 
the  latter.  The  commercial  deposits  are  usually  found  in 
pegmatite  veins,  cutting  granites,  gneisses,  and  schists.  In 
these  veins,  which  are  of  variable  width,  the  mica  is  asso- 
ciated with  quartz  and  feldspar,  being  found  in  rough 
crystals,  called  blocks  or  books,  and  which  are  either  dis- 
tributed evenly  through  the  vein  or  collected  near  its  sides. 
The  best  mica  is  obtained  from  the  more  coarsely  crystalline 
rocks ;  but  the  widest  veins  do  not  necessarily  contain  the 
largest  blocks.  As  a  rule  the  mica  does  not  form  more 
than  10  per  cent  of  the  vein,  and  usually  not  more  than  10 
or  15  per  cent  of  that  mined  can  be  cut  into  plates,  the  rest 
being  classed  as  scrap  mica. 

Mica  has  been  mined  in  a  number  of  states  both  east  and 
west,  and  in  1902  seven  states  were  producers,  of  which 
North  Carolina  was  the  most  important. 

The  use  of  mica  for  stove  doors  and  chimneys  is  decreas- 
ing, but  there  is  a  growing  demand  for  small  sheets  which 
can  be  stamped  out  into  circular  or  rectanglar  forms  and 
used  for  insulating  purposes  in  electrical  apparatus.  Scrap 
mica,  obtained  by  trimming  larger  sheets,  is  ground  for  use 
in  wall  papers,  lubricants,  boiler  coverings,  etc.  Micanite  is 
sheet  mica  obtained  by  cementing  small  clear  pieces  of  scrap 
together  under  pressure.  The  value  of  the  sheet  mica  ranges 
from  2  cents  to  $3  per  pound,  depending  on  the  size  of  the 
sheet.  Scrap  mica  sells  for  $8  to  $10  per  ton,  and  after 
grinding  for  $40  to  $60  per  ton. 

The  production  of  mica  in  1903  amounted  to  1968  short 


186         ECONOMIC   GEOLOGY   OF   THE   UNITED   STATES 

tons,  valued  at  $143,128.  Most  of  the  supply  is  imported  from 
Canada  and  India,  and  this  in  1903  amounted  to  2,251,856 
pounds,  valued  at  $466,332. 

REFERENCES  OW  MICA 

1.  Fuller,  Stone,  XIX :  530,  1899.  (Occurrences  and  uses.)  2.  Hender- 
son, Eng.  and  Min.  Jour.,  LV:  4,  1893.  (General.)  3.  Holmes, 
U.  S.  Geol.  Surv.,  20th  Ann.  Kept.,  VI  (ctd.) :  691,  1899.  (U.  S. 
deposits.)  4.  Hoskins,  Min.  Industry,  X:  458,  1902.  (N.  H.) 
5.  Pratt,  Mineral  Census  1902,  Mines  and  Quarries:  1031,  1904. 
(General.) 

MINERAL  PIGMENTS 

Under  this  head  are  included  a  number  of  mineral  sub- 
stances which  are  used  in  the  manufacture  of  paints  (5).  In 
most  cases  they  are  put  through  some  form  of  preparation 
after  mining,  such  as  grinding  or  washing.  Roasting  is  some- 
times resorted  to  for  improving  the  color. 

The  substances  commonly  used  are  iron  oxides,  barite, 
gypsum,  slate,  graphite,  asbestos,  and  soapstone. 

Hematite.  —  Certain  kinds  of  hematite,  such  as  the 
Clinton  ore  (see  Iron  Ores),  are  ground  and  sold  under 
the  name  of  metallic  paints,  and  much  used  for  coating 
wooden  surfaces  and  coloring  mortar.  The  ores  are  some- 
times roasted  before  grinding  to  improve  their  color  and 
durability.  Although  iron-ore  deposits  are  widespread, 
and  often  of  large  size,  the  quantity  of  material  suitable 
for  metallic  paint  is  small.  The  chief  supply  comes  from 
Pennsylvania,  Tennessee,  and  New  York,  and  smaller 
amounts  from  a  number  of  other  states. 

Ochers  (2,  6). — This  name  is  applied  to  powdery  limonite 
deposits  or  clays,  which,  in  their  natural  state,  contain  suf- 
ficient ferric  oxide  or  hydroxide  to  impart  a  bright  red  or 


MINOR  MINERALS  187 

yellowish-red  tint  to  the  mass.  Ocher  may  occur  as  a 
residual  product  resulting  from  the  decay  of  limestone, 
shale,  or  other  rocks,  as  a  replacement  deposit,  or  as  a  sedi- 
mentary deposit.  The  last-mentioned  form  probably  con- 
tains more  clay.  Ocher  sometimes  contains  as  much  as 
50-75  per  cent  iron  oxide  (6),  and  often  gritty  impurities, 
which  have  to  be  removed  by  washing.  Uniformity  of 
color  in  the  product  is  necessary. 

Ochers  are  classified  according  to  shade  of  color,  thus: 
yellow  ocher  is  colored  by  hydrous  iron  oxide;  red  ocher 
owes  its  color  to  ferric  oxide,  and  hence  can  be  produced 
by  roasting  yellow  ocher ;  brown  ocher  or  umber  is  colored 
by  manganese,  and  sienna  is  a  yellowish-brown  variety. 

The  most  extensive  series  of  ocher  deposits  found  in  the 
United  States  is  associated  with  the  Cambro- Silurian  strata 
of  the  Appalachians  from  Vermont  to  Alabama,  the  chief 
production  coming  from  Pennsylvania  and  Georgia.  Both 
umber  and  sienna  are  produced  in  small  quantities  in  Illinois 
and  Pennsylvania,  and  sienna  in  addition  is  obtained  from 
New  York. 

Few  paints  are  more  free  from  adulteration  than  ochers, 
for  the  reason  that  any  adulterant  that  could  be  used  is 
more  costly  than  the  ocher  itself. 

Slate.  —  The  refuse  from  slate  quarries  is  sometimes 
ground  and  sold  as  a  pigment. 

G-ypsum,1  known  also  as  terra  alba  or  mineral  white,  is 
used  to  some  extent  as  a  pigment  for  printing  wall  paper. 

Barite,1  or  barium  sulphate,  which  is  used  as  an  adulter- 
ant of  white  lead,  is  purified  after  mining  by  grinding  and 
washing. 
1  For  mode  of  occurrence  and  distribution  see  these  minerals,  pp.  139  and  170. 


188 


ECONOMIC   GEOLOGY   OF   THE   UNITED   STATES 


Asbestos1  is  used  to  some  extent  in  paint  manufacture 
for  the  so-called  non-inflammable  or  fireproof  paints,  but  the 
total  quantity  thus  utilized  is  small. 

Graphite,1  either  natural  or  artificial,  supplies  a  black 
pigment  of  permanent  color,  which,  on  account  of  its 
resistance  to  the  atmosphere  and  ordinary  chemicals,  is  of 
much  value  for  coating  oxidizable  metals,  such  as  iron  and 
steel. 

Calcium  carbonate,  in  the  form  of  chalk,  known  commer- 
cially as  whiting  or  paris  white,  is  used  as  a  pigment  to  alter 
the  shade  of  other  pigments  and  as  a  basis  for  whitewash. 

Other  paints.  —  Paints  sometimes  classed  as  mineral  paints 
are  made  from  other  crude  minerals,  as  follows :  zinc  white 
from  zinc  ore;  white  lead,  red  lead,  and  orange  mineral 
from  lead;  Venetian  red  from  iron  sulphate;  vermilion  or 
artificial  cinnabar  from  quicksilver;  chrome  yellow  from 
chromite ;  cobalt  blue  from  cobaltite. 

PRODUCTION  OF  MINERAL  PAINTS  IN  THE  UNITED  STATES  FROM 
1901  TO  1903 


1901 

1902 

1903 

QUANTITY 

QUANTITY 

QUANTITY 

SHORT 

VALUE 

SHORT 

VALUE 

SHORT 

VALUE 

TONS 

TONS 

TONS 

Ocher     .     .     . 

16,711 

$177,779 

16,565 

$145,708 

12,524 

$111,625 

Umber  .     .     . 

Sienna  .     .     . 

759 
305 

11,326 
9,304 

480 
189 

11,236  1 
4,316  J 

666 

15,367 

Metallic  paint 

15,915 

204,397 

19,020 

313,390 

25,103 

213,109 

Mortar  color  . 

9,346 

112,943 

8,355 

98,729 

10,863 

101,792 

Soapstone  .     . 

50 

350 

1,100 

2,200 





Slate.    .    .    . 

4,865 

41,211 

4,071 

39,401 

7,106 

59,029 

1  For  mode  of  occurrence  and  distribution  see  these  minerals,  pp.  167  and  178. 


MINOR   MINERALS  189 

The  imports  of  ochers  in  1903  amounted  to  9,960,334 
pounds,  valued  at  $100,447;  of  umber,  2,168,570  pounds, 
valued  at  $18,172 ;  and  of  sienna,  1,875,369  pounds,  valued 
at  $28,570.  France  is  the  largest  producer  of  ocher. 

REFERENCES  ON  MINERAL  PAINTS 

1.  Benjamin,  U.  S.  Geol.  Surv.,  Min.  Res.  1886 :  702,  1887.  2.  Hayes 
and  Eckel,  U.  S.  Geol.  Surv.,  Bull.  213 :  427,  1903.  (Georgia  ocher.) 
3.  Hill,  2d  Pa.  Geol.  Surv.,  Kept,  for  1886,  IV :  1386,  1887.  4.  Min- 
eral Industry,  IV :  491,  1896,  and  VII :  532,  1899.  5.  Struthers, 
Mineral  Census,  Kept,  on  Mines  and  Quarries,  1902 :  955,  1905. 
(General.)  6.  Watson,  Amer.  Inst.  Min.  Engrs.,  Trans.  XXXIV : 
643,  1904.  (Georgia  ocher  and  analyses.) 

MOLDING  SAND 

Certain  fine-grained  sands  and  loams  are  employed  in 
making  molds  for  castings.  Molding  sand  must  be  suf- 
ficiently fine  grained  and  aluminous  to  permit  molding  into 
the  required  form ;  strong  enough  to  hold  its  shape ;  re- 
sistant to  heat ;  and  porous  enough  to  permit  the  escape  of 
gases,  but  not  to  admit  the  melted  metal.  An  excess  of 
clay  is  undesirable,  as  it  causes  the  sand  to  shrink  and  bake 
when  the  metal  is  poured  in  it.  Molding  sands  are  obtained 
from  surface  deposits  at  many  localities,  especially  in  the 
states  east  of  the  Mississippi  River.  The  analysis  of  one 
from  Manchester,  England,  may  serve  as  a  type,  it  containing 
SiO2,  92.913;  A12O3,  5.85;  Fe2O3,  1.249;  CaO,  trace.  This 
high  silica  percentage  accounts  for  its  refractoriness,  and  its 
porosity  is  due  to  a  low  clay  content.  The  mechanical 
composition  of  molding  sands  is  probably  as  important,  if 
not  more  so,  as  their  chemical  constitution,  but  it  has  been 
little  investigated.  Many  thousands  of  tons  of  molding 
sand  are  used  annually  by  foundrymen,  but  no  statistics 


190          ECONOMIC   GEOLOGY   OF   THE  UNITED   STATES 

have  been  collected.  The  region  around  Albany,  New  York, 
supplies  enormous  quantities  of  a  fine-grained  molding  sand. 
Ohio,  Kentucky,  and  New  Jersey  are  also  important  pro- 
ducers. 

REFERENCES  ON  MOLDING  SAND 

1.  Eckel,  N.  Y.  State  Geologist,  21st  Ann.  Kept.,  1901.  2.  Merrill,  U.  S. 
National  Museum,  Guide  to  Study  of  Non-metallic  Minerals :  474, 
1901.  3.  Merrill,  Eng.  and  Min.  Jour.,  LXXVIII :  341,  1904. 
4.  See  also  forthcoming  reports,  Wis.  Geol.  Surv.  and  Va.  Geol. 
Surv. 


MONAZITE 

This  mineral  is  an  anhydrous  phosphate  of  the  rare 
earth  metals,  cerium,  lanthanum,  and  didymium,  but  its 
economic  value  is  due  chiefly  to  the  small  amount  of 
thoria  which  it  contains.  Although  grains  of  it  are  found 
scattered  through  many  granites  and  gneisses,  still  no  oc- 
currences of  this  type  are  of  any  commercial  value.  The 
economically  valuable  deposits  are  all  found  in  stream 
gravels,  derived  from  the  disintegration  of  monazite-bearing 
rocks.  Monazite  is  usually  light  yellow  to  honey  yellow, 
red,  or  brown  in  color,  has  a  resinous  luster,  and  a  specific 
gravity  of  4.64  to  5.3.  Its  gravity  and  color  aid  in  its  ready 
determination. 

In  the  United  States  deposits  of  monazite  sand  have  been 
found  in  the  granite  and  gneiss  areas  of  North  Carolina  (2) 
and  South  Carolina  (3),  and  these,  together  with  deposits 
found  in  Brazil  (1),  supply  nearly  the  entire  world's  demand. 
A  small  quantity  is  also  obtained  from  southern  Norway,  as 
a  by-product  in  feldspar  mining.  The  following  analyses 
indicate  the  composition  of  monazite  :  — 


MINOR   MINERALS 
ANALYSES  OF  NORTH  CAROLINA  MONAZITE 


191 


P205 

Ce208 

La208 

ThO2 

SiO2 

H20 

Burke  Co.,  N.  C.     .     . 

29.28 

31.28 

30.88 

6.49 

1.40 

.20 

Alexander  Co.,  N.  C.    . 

29.32 

37.26 

31.60 

1.48 

.32 

.17 

Uses. — Monazite  is  usually  separated  from  the  gravels  by 
a  washing  process,  and  in  addition  magnetic  separation  has 
in  some  cases  been  employed  to  separate  it  from  the  asso- 
ciated garnet,  magnetite,  and  quartz. 

The  value  of  monazite  lies  in  the  incandescent  properties 
of  the  oxides  of  the  rare  earths,  cerium,  lanthanum,  didym- 
ium,  and  thorium,  which  it  contains,  and  which  are  utilized 
in  the  manufacture  of  mantles  for  incandescent  lights. 

Production  of  Monazite.  —  The  production  of  monazite  for 
several  years  was  as  follows  :  — 

PRODUCTION  OF  MONAZITE  IN  THE  UNITED  STATES  FROM 
1901  TO  1903 


YEAR 

QUANTITY 

VALUE 

1901  

Pounds 

748,736 

$59,262 

1902 

802000 

64160 

1903  

862,000 

64,630 

This  quantity  represents  washed  sand  containing  85  to  99 
per  cent  monazite.  The  crude  sand  brings  from  2£  to  6 
cents  per  pound,  depending  on  the  percentage  of  thoria 
it  contains. 


REFERENCES   ON  MONAZITE 


1.  Dennis,  Min.  Indus.,  VI :  487,  1898.  (General).  2.  Nitze,  N.  C. 
Geol.  Surv.,  Bull.  9,  1895.  3.  Pratt,  U.  S.  Geol.  Surv.,  Min.  Res., 
1902  :  1003,  1903 ;  and  1903 :  1163,  1904.  (N.  C.  and  S.  C.) 


192          ECONOMIC   GEOLOGY   OF   THE  UNITED   STATES 

PRECIOUS  STONES 

The  names  gems  and  precious  stones  (1, 2)  are  applied 
to  certain  minerals,  which  on  account  of  their  rarity,  as 
well  as  hardness,  color,  and  luster  are  much  prized  for 
ornamental  use.  The  hardness  is  of  importance  as  in- 
fluencing their  durability,  while  their  color,  luster,  and 
even  transparency  affect  their  beauty.  A  distinction  is 
sometimes  made  between  the  more  valuable  stones,  or  gems 
(such  as  diamond,  ruby,  sapphire,  and  emerald),  and  the  less 
valuable,  or  precious,  stones  (such  as  amethyst,  rock  crystal, 
garnet,  topaz,  moonstone,  opal,  etc.). 

Most  gems  are  found  in  un consolidated  surface  deposits 
representing  either  residual  material,  or  alluvium  derived 
from  it,  and  in  the  latter  their  concentration  and  preserva- 
tion is  due  to  their  weight  and  hardness.  When  found  in 
solid  rock,  the  metamorphic  and  igneous  types  are  more 
often  the  source  than  the  sedimentary  ones. 

Many  different  minerals  are  used  as  gems  (1,  2),  but  only 
a  few  of  the  important  ones  can  be  mentioned  here,  and 
the  number  of  the  more  valuable  kinds  found  in  the  United 
States  is  very  limited  (7,  8,  9). 

Diamond.  —  This  mineral,  which  is  the  hardest  of  all 
known  substances,  is  pure  carbon,  crystallizes  in  the  iso- 
metric system,  and  has  a  specific  gravity  of  3.525.  It  occurs 
in  many  different  colors,  of  which  white  is  the  commonest, 
and  is  'found  either  in  basic  igneous  rocks,  or  in  alluvial 


The  massive  forms,  known  as  bort  or  carbonado,  have  little 
or  no  cleavage,  and  are  of  value  only  as  an  abrasive. 

The  greatest  number  of  diamonds  come  from  South  Africa, 


MINOR   MINERALS  193 

but  other  deposits  of  commercial  value  occur  in  India,  Borneo, 
and  Brazil. 

In  the  United  States  a  few  scattered  diamonds  have  been 
found  in  the  southern  Alleghanies,  California,  Wisconsin, 
and  Indiana,  but  they  are  all  small  (3,  4,  5,  7,  8,  9). 

Ruby.  —  A  red,  transparent  variety  of  corundum  (A12O3), 
having  a  hardness  of  9  and  a  specific  gravity  of  4.  The 
most  valuable  color  in  ruby  is  a  deep,  clear,  carmine  red. 
Rubies  of  large  size  are  scarce,  so  that  a  three- carat  stone  of 
good  color  and  flawless  is  worth  several  times  as  much  as  a 
diamond  of  the  same  size.  The  best  ones  come  from  Bur- 
ma. In  the  United  States  they  have  been  found  in  the 
stream  gravels  of  Macon  County,  North  Carolina.  Those 
found  in  Arizona  and  other  Western  states  are  not  true  rubies, 
but  a  variety  of  garnet  (7,  8,  9). 

Sapphire  is  a  blue,  transparent  variety  of  corundum 
(A12O3).  It  is  of  slightly  greater  hardness  and  specific 
gravity  than  the  ruby,  though  of  similar  composition. 
Sapphires  of  good  color  and  size  are  more  common  than 
rubies  and  cheaper.  The  best  sapphires  come  from  Siam. 
In  the  United  States  they  have  been  found  in  the  gravels  of 
Co  wee  County,  North  Carolina,  but  Yogo  Gulch,  Montana, 
where  they  are  found  in  an  igneous  dike,  is  now  the  main 
source  of  domestic  supply.  They  range  in  weight  from 
under  one  up  to  four  or  five  carats  (7,  9, 10). 

Emerald.  —  This  gem  is  a  variety  of  beryl,  essentially  a 
glucinum  aluminum  silicate.  Its  hardness  is  7.5  to  8,  and 
its  specific  gravity  2.5  to  2.7.  Its  brilliant  green  color  is 
attributed  by  some  to  chromium,  by  others  to  organic  mat- 
ter. Brazil,  Hindostan,  Ceylon,  and  Siberia  are  all  important 
sources.  In  the  United  States  a  few  have  been  found  in 


194         ECONOMIC   GEOLOGY   OF  THE   UNITED   STATES 

western  North  Carolina  (7,  9).  Flawless  emeralds  are  very 
rare,  and  equal  in  value  to  diamonds. 

Aquamarine  and  oriental  cat's-eye  are  also  varieties  of 
beryl.  Brazilian  emerald  is  a  green  variety  of  tourmaline, 
and  lithia  emerald  an  emerald-green  spodumene. 

Topaz.  —  This  is  a  fluosilicate  of  alumina,  crystallizing 
in  the  orthorhombic  system,  with  a  hardness  of  8,  specific 
gravity  of  3.5,  vitreous  luster,  and  yellow,  green,  blue,  red, 
or  colorless.  It  occurs  in  gneiss  or  granite,  as  well  as  in 
other  metamorphic  or  igneous  rocks,  and  is  associated  with 
beryl,  mica,  tourmaline,  etc.  It  is  also  found  in  alluvial  de- 
posits. The  best  gem  stones  come  from  Ceylon,  the  Urals, 
and  Brazil.  In  the  United  States  they  have  been  found  in 
small  quantities  in  Maine,  Colorado,  and  California  (7). 

Turquoise  is  a  massive  hydrated  aluminum  copper  phos- 
phate, of  waxy  luster,  blue  to  green  color,  and  opaque.  Its 
hardness  is  6,  and  specific  gravity  2.75.  It  usually  occurs  in 
streaks  and  patches  in  volcanic  rocks.  The  best  varieties 
are  obtained  from  Persia,  but  it  is  also  obtained  from  Asia 
Minor,  Turkestan,  and  Siberia.  In  the  United  States  tur- 
quoises are  found  in  the  Los  Cerrillos  Mountains  near  Santa 
Fe,  New  Mexico,  and  Turquoise  Mountain,  Arizona. 

It  is  interesting  to  note  that  turquoise  was  hardly  known  in 
the  United  States  in  1890,  but  now  the  bulk  of  the  world's  sup- 
ply comes  from  the  Southwestern  states  and  territories  (6,  7). 

Garnet.  —  Of  the  several  varieties  of  garnet,  three  are  well 
known  as  gem  stones,  viz.,  the  precious  garnet  or  alman- 
dite,  Bohemian  garnet  or  pyrope,  and  manganese  garnet  or 
spessartite.  The  first  two  are  of  deep  crimson,  the  last  of 
orange-red  or  light  red-brown  color.  India  is  the  main 
source  of  supply.  All  three  varieties  mentioned  are  found 


MINOR   MINERALS  195 

in  the  United  States,  but  there  is  a  regular  production  only 
of  the  pyrope  from  Arizona  and  New  Mexico,  and  a  purple- 
red  garnet  known  as  rhodonite  from  North  Carolina  (7,  9). 

Opal,  which  is  hydrous  silica  chemically,  is  amorphous, 
with  conchoidal  fracture,  yellow,  red,  green,  or  blue  color, 
and  often  showing  considerable  iridescence.  The  varieties 
recognized  are  the  precious  opal,  fire  opal,  girasol,  and  com- 
mon opal.  The  finest  examples  of  precious  opal  are  obtained 
from  Hungary.  Others  are  also  found  at  Queretaro,  Mexico, 
and  in  Oregon  and  Washington.  The  United  States  pro- 
duction is  small,  although  it  is  thought  that  there  are  many 
scattered  occurrences  in  the  igneous  rocks  of  Washington, 
Idaho,  Oregon,  California,  Nevada,  and  Utah  (7,  9). 

Other  Precious  Stones.  —  Among  the  other  precious  stones 
obtained  in  this  country  and  their  sources  of  supply  may  be 
mentioned :  — 

Tourmaline Maine  and  California. 

Kunzite California. 

Californite California. 

Chlorastrolite Isle  Royale. 

Fluorspar Illinois. 

Rock  crystal California. 

Amethyst Scattered  localities. 

Chrysoprase Oregon. 

Moss  agate Wyoming. 

Production  of  Precious  Stones. — The  production  of  gems  in 
the  United  States  is  not  large,  and  for  the  last  three  years 
was  as  follows :  — 

YEAH  VALUE 

1901 $289,050 

1902 328,450 

1903 321,400 

The  imports  of  diamonds  and  other  precious  stones  in 
1903  were  valued  at  $26,522,523. 


196         ECONOMIC   GEOLOGY   OF   THE   UNITED   STATES 

REFERENCES  ON  PRECIOUS  STONES 

1.  Bauer,  Edelsteinkunde.  (Leipzig,  1896.)  2.  Farrington,  Gems  and 
Gem  Minerals.  (Chicago,  1903.)  3.  Hobbs,  Amer.  Geol.,  XIV :  31, 
1894.  (Wis.  diamonds.)  4.  Hobbs,  Min.  Indus.,  IX:  301,  1901. 
5.  Hobbs,  Jour.  Geol.,  VII :  375,  1899.  (Wis.)  6.  Johnson,  Sch.  of 
Mines  Quart.,  XXIV:  493,  1903.  (N.  Hex.  Turquoise.)  7.  Kunz, 
Mineral  Census,  1902,  Mines  and  Quarries.  (General  on  United 
States  Gems.)  8.  Kunz.  See  Chapters  on  Precious  Stones  in  Min- 
eral Resources,  issued  annually  by  U.  S.  Geol.  Surv.  9.  Kunz,  Gems 
and  Precious  Stones  of  N.  Amer.  (New  York,  1892.)  10.  Pratt, 
U.  S.  Geol.  Surv.,  Bull.  180,  1901.  (Sapphire.)  11.  Reid,  Eng. 
and  Min.  Jour.,  LXXV:  786,  1903.  (Burro  Mtn.  Turquoise  dist.) 
12.  Streeter,  Precious  Stones  and  Gems  (London),  1892. 


SULPHUR  AND  PYRITE 

These  two  minerals  are  discussed  in  the  same  chapter 
because  they  both  serve  as  sources  of  sulphur. 

Sulphur.  —  The  occurrences  of  native  sulphur  are  of  two 
types  (4)  :  (1)  the  Solfataric  type  and  (2)  the  Gypsum  type. 

Solfataric  Type.  —  Sulphur  is  often  found  in  fissures  of 
lava  and  tuff  around  many  active  and  also  extinct  volcanic 
vents,  being  deposited  by  the  oxidation  of  hydrogen  sulphide, 
or  by  the  sulphuretted  hydrogen  and  sulphur  dioxide,  in  the 
presence  of  moisture,  yielding  water  and  sulphur.  Ferric 
chloride  is  sometimes  deposited  under  the  same  conditions, 
and  might,  owing  to  its  similar  color,  be  at  first  mistaken 
for  sulphur. 

Deposits  of  the  solfataric  type  are  rarely  of  commercial 
importance,  but  in  foreign  countries  they  are  worked  in 
Japan,  and  also  in  the  crater  of  Popocatepetl,  in  Mexico. 

In  the  United  States  a  deposit  is  known  to  exist  in  Beaver 
County,  southwestern  Utah  (4, 5).  The  sulphur  is  found 
impregnating  volcanic  tuffs,  sand  (the  product  of  decom- 


MINOK   MINERALS  197 

position),  or  in  the  fissures  in  trachyte  and  carboniferous 
limestone.  The  deposit  is  said  to  be  30  feet  thick  and  the 
deposition  still  continues.  Small  amounts  are  mined  in 
Oregon  and  Nevada  (l),  but  the  output  is  irregular. 

G-ypsum  Type.  —  This  is  formed  by  the  action  of  bitumi- 
nous matter  on  gypsum,  the  former  having  a  reducing  effect. 
It  is,  therefore,  always  found  in  sedimentary  rocks,  in  which 
marls,  limestones,  and  shales  are  prominent. 

The  change  involved  is  a  reduction  of  the  calcium  sul- 
phate of  the  gypsum,  to  calcium  sulphide,  with  the  produc- 
tion also  of  carbon  dioxide  and  water.  The  sulphide  then, 
by  reaction  with  the  carbon  dioxide  of  the  air,  and  water, 
yields  calcium  carbonate,  native  sulphur,  and  hydrogen 
sulphide. 

This  type  of  sulphur  is  often  of  great  economic  value,  and 
deposits  are  found  in  a  number  of  countries.  The  beds  are 
mostly  of  Tertiary  age,  but  Jurassic  ones  are  also  known. 

In  the  United  States  the  richest  and  best  known  is  found 
in  southwestern  Louisiana  (6,  8).  Here  a  bed  of  sulphur 
over  100  feet  thick  was  discovered  in  boring  for  oil.  It 
is  underlain  by  gypsum  and  salt,  and  covered  by  300  to  400 
feet  of  wet  clay,  quicksand,  and  gravel,  which  has  presented 
great  difficulties  in  all  attempts  to  mine  the  material.  Its 
extraction  is  now  accomplished  by  means  of  superheated 
steam. 

Sicily  is  the  most  important  source  of  supply  for  the  United  States. 
There  the  sulphur  is  found  in  veinlets  and  cavities  in  a  cellular  Miocene 
limestone,  which  underlies  and  overlies  gypsum.  The  sulphur-bearing 
beds  are  generally  from  3  to  10  feet  thick,  and  vary  in  their  thickness 
as  well  as  dip,  the  latter  being  from  25°  up  to  70°.  The  percentage  of 
sulphur  varies  from  8  to  25  per  cent,  the  first  figure  representing  the 


198 


ECONOMIC  GEOLOGY  OF  THE  UNITED  STATES 


lowest  economic  limit.  The  mines  contain  more  or  less  petroleum  and 
bitumen,  and  sometimes  even  explosive  gases,  while  barite  and  celestite 
are  associated  minerals.  Owing  to  improper  methods  of  mining  there 
is  much  waste. 

Uses.  —  The  most  important  use  of  sulphur  is  for  the 
manufacture  of  sulphuric  acid,  and  in  paper  manufacture. 
Some  is  also  used  in  making  matches,  for  medicinal  purposes, 
and  in  making  gunpowder,  fireworks,  insecticides,  for  vul- 
canizing india  rubber,  etc. 

In  recent  years  pyrite  has  largely  replaced  sulphur  for 
the  manufacture  of  sulphuric  acid,  and  the  increase  in  price 
of  Sicilian  sulphur  has  helped  this. 

The  greater  portion  of  the  world's  supply  of  sulphur  is 
obtained  from  Sicily,  the  United  States  consuming  the 
largest  amount. 

Production  of  Sulphur.  —  The  value  of  the  domestic  pro- 
duction and  imports  of  sulphur  for  several  years,  as  well 
as  total  domestic  consumption,  which  includes  sulphur 
obtained  from  pyrite,  are  given  in  the  following  table  :  — 

IMPORTS  AND  PRODUCTION  OF  SULPHUR  IN  THE  UNITED  STATES 


DOMESTIC 
PRODUCTION 

IMPORTS 

TOTAL 
CONSUMPTION 

1893  

Long  tons 
1,071 

Long  tons 

105,823 

Long  tons 

228,709 

1895  

1,607 

122,096 

254,196 

1900  .     .     . 

3  147 

167  696 

408  038 

1901  

6806 

175,210 

469,415 

The  sulphur  imported  into  the  United  States  comes 
chiefly  from  Sicily  and  Japan,  with  very  small  quantities 
from  Mexico  and  Chile. 


MINOR   MINERALS  199 

REFERENCES  ON  SULPHUR 

1.  Adams,  U.  S.  Geol.  Surv.,  Bull.  225 :  497, 1904.  (Nevada.)  2.  Eng. 
and  Min.  Jour.,  XLVI:  174,  1888.  (Sicily.)  3.  Eng.  and  Min. 
Jour.,  LXXVII :  523, 1904.  (Sicily.)  4.  Kemp,  Min.  Indus.,  II :  585, 
1894.  (General.)  5.  Russell,  Trans.,  N.  Y.  Acad.  Sci.,  1 :  168,  1882. 
(Utah  and  Nevada.)  6.  Preussner,  Zeitschr.  d.  d.  Geol.  Gesell., 
XL:  194,  1888.  (La.)  7.  Richardson,  U.  S.  Geol.  Surv.,  Bull. 
260 :  589,  1905.  (El  Paso  Co.,  Tex.)  8.  Anon.,  Eng.  and  Min. 
Jour.,  LXXVIII:  592,  1904.  (La.) 

Pyrite.  —  Pyrite,  the  sulphide  of  iron,  is  widely  distrib- 
uted in  nature,  being  found  in  many  kinds  of  rocks  and 
in  all  formations.  It  occurs  in  a  variety  of  forms,  such 
as  disseminations,-  contact  deposits,  concretionary  masses, 
fissure  veins,  and  lenticular  deposits,  the  last  form  being 
characteristic  of  most  of  those  occurrences  which  are  of 
commercial  value.  As  mined,  pyrite  usually  contains  small 
quantities  of  other  metallic  minerals  as  well  as  silica  and 
alumina ;  but  if  its  sulphur  content  falls  below  50  per  cent, 
it  is  not  salable.  The  following  analysis  of  pyrite  from 
Louisa  County,  Virginia,  will  serve  as  illustration.  It  is: 
S,  47.76;  Fe,  43.99;  Cu,  3.69;  Zn,  .24;  SiO2,  1.99;  As, 
.63;  Pb,  .10.  If  chalcopyrite  is  present  and  exceeds  3  or 
4  per  cent,  the  rock  may  be  used  as  copper  ore.  Pyrrhotite 
is  abundant  in  some  of  the  Virginia  deposits. 

Distribution.  —  The  most  important  domestic  occurrences 
are  found  in  a  belt  of  metamorphic  rock  extending  from 
New  Hampshire  to  Alabama  (4),  in  which  the  pyrite  is 
found  forming  lenses  in  metamorphic  rocks.  Massachusetts 
and  Virginia  are  the  most  important  producers.  New  York 
also  contributes.  In  Louisa  County,  Virginia  (2),  the  pyrite 
lenses  occur  in  Cambro-Silurian  slates  and  schists.  The 


200         ECONOMIC   GEOLOGY   OF   THE   UNITED   STATES 

deposits  are  known  to  be  over  2  miles  in  length,  and  have 
been  exploited  to  a  depth  of  600  feet,  while  their  average 
thickness  is  18  feet.  Their  origin  is  somewhat  obscure 
and  depends  on  the  character  of  the  original  rock. 

Some  pyrite  is  obtained  from  Indiana  and  Ohio,  from 
"coal  brasses"  obtained  as  a  by-product  in  coal  mining  (3). 

Uses.  —  Pyrite  is  used  chiefly  and  in  increasing  quanti- 
ties for  the  manufacture  of  sulphuric  acid  and  sulphate  of 
iron,  while  small  amounts  are  consumed  in  the  manufac- 
ture of  mineral  paint.  It  is  not  used  as  an  ore  of  iron. 
Recent  experiments  have  demonstrated  the  possibility  of 
saving  the  sulphuric  acid  gas  from  the  roasting  of  zinc 
ores,  and  the  utilization  of  pyrrhotite  for  making  sulphur 
and  sulphuric  acid. 

REFERENCES  ON  PYRITE 

1.  Adams,  Trans.  Amer.  Inst.  Min.  Engrs.,  XII:  527,  1883.  (Va.) 
2.  Nason,  Eng.  and  Min.  Jour.,  LVII :  414,  1894.  (Va.)  3.  Struthers, 
Min.  Indus.,  XI :  577,  1903.  4.  Wendt,  S.  of  M.  Quart.,  VII :  218, 
1885.  (Alleghanies.) 

STRONTIUM 

The  two  minerals  serving  as  sources  of  strontium  salts  are 
celestite  (SrSO4)  and  strontianite  (SrCO3).  Of  these  two 
the  former  is  the  more  important,  but  the  latter  is  the  more 
valuable,  as  the  strontium  salts  can  be  more  easily  extracted 
from  it. 

Both  celestite  and  strontianite  have  been  found  at  a  num- 
ber of  localities  in  the  United  States,  but  seldom  in  large 
quantities.  One  important  deposit  of  celestite  has  been 
found  in  limestone  caves  near  Put  in  Bay,  Strontian  Island, 


MINOK   MINERALS  201 

in  Lake  Erie,  and  in  opening  up  the  cave  150  tons  of  the 
mineral  were  taken  out.  Similar  occurrences  have  been 
found  in  limestones  in  other  states,  but  none  of  them  have 
any  commercial  value. 

Nearly  all  the  strontium  salts  now  used  in  the  United 
States  are  imported  from  Germany,  the  crude  material  being 
obtained  in  part  from  Westphalia,  Germany,  and  also  from 
Thuringia,  Germany,  and  Sicily. 

Uses.  —  Strontium  salts  are  used  in  sugar  refining,  in  fire- 
works manufacture,  and  to  a  small  extent  in  medicine. 

REFERENCES  ON  STRONTIUM 

1.  Pratt,  U.  S.  Geol.  Surv.,  Min.  Res.,  1901 :  955,  1902. 

TALC  AND  SOAPSTONE 

Talc,  a  silicate  of  magnesia,  is  a  widely  distributed  mineral, 
but  rarely  occurs  in  large  quantities.  It  commonly  repre- 
sents the  alteration  product  of  other  magnesian  minerals, 
such  as  tremolite,  actinolite,  pyroxene,  or  enstatite,  and  is 
therefore  often  associated  with  talcose  or  chlorite  schists, 
serpentine,  and  such  basic  igneous  rocks  as  peridotite.  It  is 
also  found  associated  with  dolomite.  In  the  southern  Ap- 
palachians the  alteration  of  enstatite  rocks  into  talcose  rocks 
has  given  rise  to  extensive  soapstone  deposits,  soapstone 
being  an  impure  massive  form  of  talc. 

Large  deposits  of  pure  talc,  usually  massive,  though  in 
places  with  a  fibrous  structure,  are  found  in  North  Caro- 
lina (1).  These  beds,  which  are  associated  with  marble  and 
quartzite,  have  apparently  been  formed  by  the  alteration  of 
bands  of  tremolite  bedded  with  the  other  rocks.  Those 
portions  discolored  by  iron  oxide,  or  containing  tremolite 


202 


ECONOMIC  GEOLOGY  OF  THE  UNITED  STATES 


crystals,  are  of  no  value.  A  fibrous  talc  formed  by  the 
alteration  of  tremolite  or  enstatite  occurs  in  St.  Lawrence 
County,  New  York  (3),  where  it  is  bedded  with  limestone 
and  tremolite  or  enstatite  schist.  From  these  two  regions 
most  of  the  talc  of  the  country  is  derived ;  but  soapstone  is 
obtained  from  a  number  of  states,  of  which  Virginia  is  the 
most  important  producer. 

The  following  analyses  from  several  localities  show  the 
kind  and  quantity  of  impurities  which  good  talc  may  con- 
tain :  — 

ANALYSES  OF  COMMERCIAL  TALC 


H2O 

LOCALITY 

Si02 

A1208 

FeO 

CaO 

MgO 

Na2O 

K2O 

Loss  on 
Igni- 

tion 

Kinsey  Mine, 

N.C.     .    . 

63.07 

1.56 

.67 

.30 

28.76 

.78 

Tr 

4.36 

St.  Lawrence 

MnO 

Co.,N.Y.  . 

62.10 

1.30 

32.40 

2.15 

2.05 

Uses.  —  Talc  is  marketed  as  rough  talc,  sawed  slabs,  or 
ground  talc.  Its  peculiar  physical  character,  extreme  fine- 
ness, softness,  and  freedom  from  grit,  adapt  it  to  a  number  of 
uses,  of  which  the  following  are  most  important :  fireproof 
paints,  electric  insulators,  foundry  facings,  boiler  and  steam- 
pipe  coverings,  soap  adulterants,  toilet  powders,  dynamite, 
in  wall  plasters,  for  dressing  skins  and  leather,  as  a  base  for 
lubricants,  and  as  a  filling  for  paper.  Most  of  the  New 
York  fibrous  talc  is  used  for  the  last  purpose,  being  better 
suited  for  it  than  the  North  Carolina  product.  The  com- 
pact varieties  of  pure  talc  are  employed  for  pencils,  and 
for  coal-  and  acetylene-gas  tips. 


MINOR   MINERALS 


203 


Pyrophyllite  differs  from  talc  chemically,  being  a  hydrous 
aluminum  silicate,  instead  of  a  magnesium  silicate,  but  when 
sufficiently  free  from  grit  it  is  put  to  the  same  use  as  talc. 
It  is  sometimes  incorrectly  called  agalmatolite,  because  of 
its  resemblance  to  the  true  mineral  of  that  name.  Deposits, 
more  extensive  than  those  of  talc,  are  found  near  Glendon, 
North  Carolina  (1).  It  varies  from  green  and  yellowish 
white  to  white,  but  in  all  cases  becomes  nearly  white  when 
dried. 

Production  of  Talc  and  Soapstone.  —  The  production  for 
the  last  three  years  has  been  as  follows :  — 

PRODUCTION  OF  TALC  AND  SOAPSTONE  FROM  1901  TO  1903 


1901 

1902 

1903 

Short 
tons 

Value 

Short 
tons 

Value 

Short 
tons 

Value 

New  York  (6)       .    . 

69,200 

$483,600 

71,100 

$615,350 

60,230 

$421,600 

693 

4  717 

(c) 

(c) 

1  012 

9042 

North  Carolina     .    . 

5,819 

77,824 

5,239 

88,962 

5,330 

76,984 

N.  Jersey  and  Pa.     . 

2,552(a) 

19,132(a) 

7,082 

52,812 

5,412 

44,058 

Indiana  and  Virginia 

12,511 

232,900 

13,221 

372,163 

13,118 

243,552 

Other  states  (d)    .    . 

7,068 

90,315 

1,312 

11,220 

1,799 

44,824 

(a)  Pennsylvania  alone.  (6)  Fibrous  talc,  (c)  California,  Maryland, 
Massachusetts,  New  Hampshire,  New  Jersey,  and  Vermont  in  1901  ;  Cali- 
fornia, Massachusetts,  and  Georgia  in  1902  ;  California,  Massachusetts,  and 
Vermont  in  1903. 

The  imports  in  1903  amounted  to  1791  short  tons,  valued 
at  $19,677. 

REFERENCES  ON  TALC  AND  SANDSTONE 

1.  Pratt,  N.  C.  Geol.  Surv.,  Econ.  Papers,  No.  3,  1900.  (N.  Ca.)  2.  Rand, 
Philadelphia  Acad.  Nat.  Sci.,  Proc.  1894:  455.  3.  Smyth,  School 
of  Mines  Quart.,  XVII:  333,  1896.  (N.  Y.  and  bibliography.) 
4.  Waldo,  Mineral  Industry,  II :  603,  1894. 


CHAPTER  XI 
MINERAL  WATERS 

THIS  term  is  commonly  applied  to  those  spring  waters 
containing  a  variable  amount  of  dissolved  solid  matter  of 
such  character  as  to  make  them  of  medicinal  value.  Their 
origin,  although  often  regarded  as  curious,  is  simple,  the 
dissolved  substances  having  been  derived  from  the  rocks 
through  which  the  spring  waters  have  circulated.  Many 
mineral  waters  contain  carbonic  and  even  other  acids,  and 
alkalies,  which  further  increase  their  powers  of  solution. 
There  is  apparently  some  connection  between  hot  mineral 
springs  and  geological  structure,  as  they  are  more  abundant 
in  regions  of  faulting  or  recent  volcanic  activity.  Mineral 
waters  derived  from  sedimentary  rocks  usually  show  a 
greater  quantity  of  dissolved  material  than  those  occur- 
ring in  igneous  rocks. 

Springs  whose  temperature  is  above  70°  F.  are  termed 
thermal,  those  between  70°  F.  and  98°  F.  being  classed  as 
tepid,  and  those  hotter  than  this  as  hot  springs.  The  fol- 
lowing will  serve  as  examples  to  show  the  temperature  of 
different  thermal  springs :  Sweet  Springs,  West  Virginia, 
74°  F. ;  Warm  Springs,  French  Broad  River,  Tennessee,  95°; 
Washita,  Arkansas,  140°  to  156°;  San  Bernardino  Hot 
Springs,  California,  108°  to  172°;  Las  Vegas,  New  Mexico, 
110°  to  140°. 

The  volume  of  discharge  shown  by  mineral  springs  is 
204 


MINERAL   WATERS  205 

quite  variable.  The  famous  Orange  Spring  of  Florida 
discharges  5,055,000  gallons  per  hour,  while  others  are 
as  follows :  Champion  Springs,  Saratoga,  New  York,  2500 
gallons ;  Roanoke  Red  Sulphur  Springs,  Virginia,  1278  gal- 
lons ;  Warm  Sulphur  Springs,  Bath,  Virginia,  360,000  gal- 
lons ;  Glen  Springs,  Waukesha,  Wisconsin,  45,000  gallons. 

While  a  classification  of  mineral  waters  may  be  geo- 
graphic, geologic,  therapeutic,  or  chemical,  that  prepared 
by  A.  C.  Peale  is  perhaps  as  satisfactory  as  any.  He  sub- 
divides mineral  waters  into  the  following  classes :  — 

Alkaline 

Sulphated 


Alkaline-saline  .  . 

( Muriated 

( Sulphated 
Saline    .     .     .  \         . 

I  Muriated 

( Sulphated 

Acid       .     .     .  |  Muriated 

{ Sulphated 
I  Siliceous  \  , 

I  Muriated 

The  springs  falling  in  the  above  groups  may  be  either 
thermal  or  non-thermal,  and  may  be  either  free  from  gas 
or  contain  CO2,  H2S,  N,  or  CH4. 

Distribution  of  Mineral  Waters  in  the  United  States.  — 
There  are,  according  to  Peale,  between  eight  and  ten  thou- 
sand mineral  springs  in  the  United  States,  and  of  this 
number  725  were  producing  in  1903.  The  majority  of  the 
commercially  valuable  mineral  springs  are  located  in  the 
eastern  United  States  and  Mississippi  Valley.  West  of 
the  101st  meridian  they  are  confined  chiefly  to  the  Pacific 
coast.  No  thermal  springs  are  known  in  the  New  England 


206 


ECONOMIC   GEOLOGY   OF   THE  UNITED   STATES 


states.  Among  the  American  springs,  those  at  Saratoga, 
New  York,  have  an  international  reputation,  and  compare 
well  with  many  of  the  foreign  ones.  Others  of  importance 
are  the  Hot  Springs  of  Virginia  and  the  Hot  Springs  of 
Arkansas. 

The  following  table  contains  the  analyses  of  several  types 
of  mineral  waters  from  the  United  States :  — 

ANALYSES  OF  AMERICAN  MINERAL  WATERS 


s 

I 

J 

* 

1 

i^l 

1£ 

02 

|| 

1  H-  5  g 

|gl 

fl| 

CHEMICAL  CONSTITUENTS 

!  g  g 

°°     < 
pj     0    ,"1 

s  ^ 

f! 

gfcoS   | 

I  a'o 

111 

HP 

OQ    K 

Jill 

ij  | 

III 

1*1 

P! 

^     o 

2  * 

gig! 

t-5       < 

M      •< 

gr.  per 

gr.  per 

gr.  per 

gr.  per 

gr.  per 

gr.  per 

gr.  per 

gal. 

gal. 

gal. 

gal. 

gal. 

gal. 

gal. 

Sodium  carbonate  .... 

5.00 

Sodium  bicarbonate    .    .    . 

10.77 

8.75 





.49 

_ 

1.26 

Sodium  sulphate     .... 











16.27 

.54 

Calcium  carbonate  .... 





5.22 

Magnesium  carbonate     .     . 

— 



3.17 

— 

11.41 

— 

Calcium  bicarbonate  .    .    . 

143.40 

41.32 

— 

12.66 

12.93 



17.02 

Magnesium  bicarbonate  .    . 

121.76 

29.34 

— 



.69 



12.39 

Lithium  bicarbonate  .    .    . 

4.76 

— 

— 

— 

— 

Trace 

— 

Iron  bicarbonate     .... 

.34 

3.00 

— 

2.17 

— 



.04 

Magnesium  sulphate  .    .    . 

— 

2.15 

— 



18.96 





Potassium  sulphate     .    .    . 

.89 

— 

1.38 

— 

— 

— 

— 

Sodium  chloride      .... 

400.44 

166.81 

— 

— 

.33 

27.34 

.46 

Potassium  chloride      .    .    . 

8.05 

— 

— 

— 

— 

— 

1.16 

Potassium  bromide     .    .    . 

— 

1.57 

— 

— 

— 

— 

— 

Sodium  bromide     .... 

8.56 

— 

— 

— 

— 

— 

— 

Sodium  iodide    

.14 

4.67 

Silica     

.84 

.53 

1.72 

.38 

.45 

2.51 

.74 

Calcium  sulphate    .... 

— 

— 

14.53 

2.54 

96.64 

— 

Production  of  Mineral  Waters.  —  The  production  of 
mineral  waters  in  the  United  States  for  the  last  three 
years  was  as  follows :  — 


MINERAL   WATERS 


207 


PRODUCTION  OF  MINERAL  WATERS  IN  UNITED  STATES  FROM  1901 
TO  1903 


YEAR 

QUANTITY 
GALLONS 

VALUE 

1901          

55,771,188 

$7,586,962 

1902                         .          

64,859,451 

8,793,761 

1903     

51,242,757 

9,041,078 

The  production  of  the  more  important  states  in  1903  was 
as  follows :  — 

PRODUCTION  OF  MINERAL  WATERS  IN  SEVERAL  STATES  IN  1903 


STATE 

QUANTITY 
GALLONS 

VALUE 

New  York              

1  827  408 

$1,432,801 

1  293  777 

1  058  954 

1,862,855 

706,372 

Virginia 

2  561  502 

477  410 

1  522,860 

357,579 

REFERENCES  ON  MINERAL  WATERS 

1.  Bailey,  Kas.  Geol.  Surv.,  VII,  1902.  (Kas.)  2.  Branner,  Ark.  Geol. 
Surv.,  Kept.,  I,  1891.  (Ark.)  3.  Crook,  Mineral  Waters  of  United 
States  and  their  Therapeutic  Value.  (N.  Y.  1899.)  4.  Lane,  U.  S. 
Geol.  Surv.,  Water  Supply  Bull.  XXXI,  1899.  5.  Peale,  U.  S.  Geol. 
Surv.,  14th  Ann.  Kept.,  11:  51.  (U.S.)  6.  Schweitzer,  Mo.  Geol. 
Surv.,  Ill,  1892.  (Mo.,  also  general.) 

UNDERGROUND    WATERS 

While  much  of  the  water  used  for  supplying  towns  and 
cities,  for  irrigation  purposes,  etc.,  is  obtained  from  below 
the  surface,  all  of  it  originates  in  rainfall.  The  rain  water 
falling  on  the  surface  is  disposed  of  in  part  by  evaporation 
and  surface  run-off,  but  a  variable  and  sometimes  large  per- 
centage seeps  into  the  ground. 


208          ECONOMIC   GEOLOGY   OF   THE   UNITED   STATES 

Ground  Water  (22). — Of  this  portion  soaking  into  the 
ground,  a  small  part  is  retained  by  capillarity  in  the  surface 
soil,  to  be  returned  again  to  the  atmosphere  either  by  direct 
evaporation  or  through  plants,  but  most  of  it  finds  its  way 
into  the  deeper  layers  of  the  soil,  which  it  completely 
saturates. 

The  water  in  this  saturated  zone,  which  is  termed  the  ground 
water,  forms  a  great  reservoir  of  supply  for  lakes,  springs,  and 
wells,  and  its  upper  surface,  known  as  the  water  table,  agrees 
somewhat  closely  with  that  of  the  land  surface,  but  is  nearer 


FIG.  34.  —  Ideal  section  across  a  river  valley,  showing  the  position  of  ground 
water  and  the  undulations  of  the  water  table  with  reference  to  the  surface 
of  the  ground  and  bed  rock.  After  Schlichter,  U.  S.  Geol.  Surv.,  Water 
Supply  Bull.  67 : 1. 

to  it  under  valleys,  and  farther  from  it  under  hills  (Fig.  34). 
The  depth  of  the  water  table  is  quite  variable,  being  but  a 
few  feet  below  the  surface  in  moist  climates,  while  in  arid 
regions  it  may  be  100  feet  or  more.  In  any  area,  however, 
the  water  table  may  show  periodical  fluctuations.  In  all 
ground  water  there  is  a  slow  but  constant  movement  from 
higher  to  lower  levels,  just  as  in  the  case  of  surface  waters, 
so  that  the  ground  water  flows  towards  the  valleys.  There 
it  may  discharge  into  the  streams,  but  in  some  instances 
it  follows  the  valley  bottom  below  the  river  bed,  separated 
from  the  river  water  by  a  more  or  less  impervious  layer  (22). 
The  composition  of  the  ground  water  also  shows  a  somewhat 
close  relation  to  the  rocks  or  soils  in  which  it  accumulates. 


MINERAL  WATERS  209 

Artesian  Water.  —  In  some  areas  much  of  the  water  which 
percolates  through  the  soil  is  caught  up  by  porous  beds  of 
sandstone,  gravel,  or  in  rarer  instances  limestone,  and  where 
these  are  between  impervious  beds  such  as  shale,  the  absorbed 
water  may  follow  them  for  some  distance,  especially  if  the 
porous  stratum  is  inclined.  Water  thus  confined  is  under 
pressure,  and  tends  to  rise  towards  the  surface  along  any 
path  of  escape  open  to  it,  such  as  joint  or  fault  planes,  or 
where  the  water-bearing  bed  is  cut  into  by  a  stream.  A  drill 
hole  bored  to  tap  the  water-bearing  bed  serves  the  same  pur- 
pose ;  and  when  the  pressure  is  sufficient  to  force  the  water 
upward  so  that  it  flows  from  the  tube,  it  is  called  an  arte- 
sian well.  The  term  is  however  rather  loosely  used  now  and 
applied  to  many  deep  wells  which  are  not  flowing. 

The  requisite  conditions  (1)  for  a  supply  of  artesian  water 
are :  (1)  a  porous  stratum  ;  (2)  an  impervious  bed  below  and 
above  the  water-bearing  bed ;  (3)  inclined  beds,  so  that  the 
point  of  intake  or  fountain  head  can  be  higher  than  the  well ; 
(4)  a  sufficient  area  of  outcrop  or  collecting  area  to  obtain  a 
large  enough  supply  —  this  may  be  many  miles  from  the 
well ;  (5)  adequate  rainfall ;  (6)  absence  of  escape  for  the 
water  at  a  lower  level  than  the  surface  at  the  well.  Artesian 
water  was  formerly  looked  for  only  in  synclinal  basins,  but 
it  is  now  known  that  sedimentary  beds  may  be  water  bear- 
ing in  areas  of  monoclinal  dip. 

Artesian  wells  vary  greatly  in  their  capacity  and  depth. 
Some  are  not  more  than  100  feet  deep,  while  others  are  2000 
or  more  feet  deep. 

Though  the  most  productive  artesian  wells  are  found  in 
pre-Pleistocene  sedimentary  rocks  of  regular  structure  (Fig. 
35),  still,  flowing  artesian  wells  even  of  large  capacity  are 


210          ECONOMIC   GEOLOGY   OF   THE   UNITED  STATES 

at  times  found  in  the  glacial  drift  where  water-bearing 
lenses  of  sand  or  gravel  are  overlain  or  surrounded  by 
clay. 

Even  in  areas  of  igneous  and  metamorphic  rocks  the  water 
seeps  in  along  joint  planes,  and  collects  at  times  in  sufficient 
quantities  to  serve  as  a  source  of  supply  which  may  even  be 
under  pressure  (6,  paper  by  G.  O.  Smith). 


FIG.  35.  —  Geologic  section  of  Atlantic  Coastal   Plain,  showing  water-bearing 
horizons.    After  Barton,  Amer.  Inst.  Min.  Engrs.,  Trans.  XXIV:  375. 

Artesian  wells  are  to  be  distinguished  from  ground  water 
wells  by  their  greater  constancy,  absence  of  relation  to  sur- 
rounding climatic  conditions,  and,  in  moist  climates  at  least, 
of  a  high  constituent  of  mineral  matter. 

There  are  many  areas  in  the  United  States  in  which  the 
conditions  are  favorable  to  an  artesian  water  supply,  as  the 
various  state  and  government  reports  will  show.  A  few  of 
the  more  important  may  be  briefly  referred  to. 

Along  the  Atlantic  and  Gulf  Coastal  Plain  an  abundant 
supply  of  artesian  water  is  obtained  from  the  Cretaceous 
and  Tertiary  beds,  at  depths  varying  from  50  feet  along 


MINERAL   WATEKS  211 

the  inland  border,  to  1000  feet  and  over  along  the  coast  (4) 
(Fig.  35). 

A  second  area  is  that  of  the  upper  Mississippi  Valley  (19), 
in  which  an  abundant  supply  of  potable  water  is  obtained 
from  the  St.  Croix  and  St.  Peters  sandstone,  whose  outcrop 
in  Minnesota  and  Wisconsin  covers  some  14,000  square  miles. 

In  the  Great  Plains  (2)  region  water  is  obtained  from  the 
Dakota  sandstone,  whose  collecting  area  is  around  the  border 
of  the  Black  Hills  (Fig.  36).  This  source  is  available  in 


FIG.  36.  —  Section  from  Black  Hills  across  South  Dakota,  showing  artesian  well 
conditions.    After  Darton. 

South  Dakota  and  eastern  Nebraska  and  Kansas.     The  chief 
use  of  the  water  in  this  region  is  for  irrigation. 

For  the  arid  regions  of  the  West  this  source  of  supply  has 
been  of  inestimable  value,  and  has  been  the  means  of  reclaim- 
ing many  an  area  of  hitherto  useless  land. 

REFERENCES  ON  UNDERGROUND  WATER 

1.  Chamberlin,  U.  S.  Geol.  Surv.,  5th  Ann.  Kept. :  125,  1885.  (Artesian 
water  supply.)  2.  Darton,  U.  S.  Geol.  Surv.,  Prof.  Paper  32,  1905. 
(Central  Great  Plains.)  3.  Darton,  U.  S.  Geol.  Surv.,  Water  Supply 
Bulls.  57  and  161.  (List  of  deep  borings  in  United  States.)  4.  Darton, 
U.  S.  Geol.  Surv.,  Bull.  138,  1896.  (Atlantic  Coastal  Plain.)  5.  El- 
dridge,  U.  S.  Geol.  Surv.,  Mon.  27.  (Denver  basin.)  6.  Fuller  and 
others,  U.  S.  Geol.  Surv.,  Water  Supply  Bull.  114,  1905.  (Under- 
ground waters,  E.  United  States.)  7.  Fuller,  U.  S.  Geol.  Surv., 
Water  Supply  Bull.  100,  1905.  (Hydrography  E.  United  States.) 
8.  Gilbert,  U.S.  Geol.  Surv.,  17th  Ann.  Kept.,  II:  557, 1896.  (Arkansas 


212          ECONOMIC   GEOLOGY   OF   THE   UNITED   STATES 

Valley,  Col.)  9.  Hall,  Ala.  Geol.  Surv.,  Bull.  7.  (Ala.)  10.  Hill,  U.S. 
Geol.  Surv.,  21st  Ann.  Rept.,VII :  387, 1901.  (Tex.)  11.  Holmes,  Amer. 
Inst.  Min.  Engrs.,  Trans.  XXV:  936,  1896.  (Piedmont  plateau.) 
12.  King,  U.  S.  Geol.  Surv.,  19th  Ann.  Kept.,  II :  59,  1899.  (Under- 
ground water  circulation.)  13.  Knight,  Wyo.  Univ.  Exp.  Sta.,  Bull. 
45, 1900.  (Wyo.)  13  a.  Lane,  U.  S.  Geol.  Surv.,  Water  Supply  Bulls. 
30  and  31, 1899.  (Mich.)  14.  Leverett,  U.  S.  Geol.  Surv.,  17th  Ann. 
Kept.,  II:  701,  1896.  (111.)  15.  Leverett,  U.  S.  Geol.  Surv.,  Water 
Supply  Bulls.  26  and  21.  (Ind.)  16.  Singley,  Texas  Geol.  Surv.,  4th 
Ann.  Kept. :  87.  (Galveston  well.)  17.  McCallie,  Ga.  Geol.  Surv., 
Bull.  7, 1899.  (Ga.)  18.  McGee,  U.  S.  Geol.  Surv.,  14th  Ann.  Kept., 
II :  1.  (E.  United  States.)  19.  Norton,  la.  Geol.  Surv.,  VI :  115, 
1897.  (Iowa.)  20.  Orton,  U.S.  Geol.  Surv.,  19th  Ann.  Kept.,  IV:  640, 
1899.  (Ohio  rock  waters.)  21.  Ruddy,  Wash.  Geol.  Surv.,  1 :  296, 
1901.  (Wash.)  22.  Slichter,  U.  S.  Geol.  Surv.,  Water  Supply  Paper 
No.  67, 1902.  (General  on  underground  waters.)  23.  Woolman,  see 
various  annual  reports  N.  J.  Geol.  Surv.  Many  other  papers  in 
Water  Supply  and  Irrigation  bulletins  issued  by  U.  S.  Geol.  Surv. 


CHAPTER  XII 
SOILS 

THE  term  soil  is  applied  to  the  upper  few  inches  of  the 
mantle  of  unconsolidated  material  (regolitTi)  which  covers 
the  earth's  surface,  and  which  is  composed  of  a  mixture  of 
rock,  sand,  and  clay  fragments  in  all  stages  of  decay ;  with 
it  there  is  usually  mixed  a  variable  amount  of  decayed  and 
decaying  organic  matter  (humus). 

Origin.  —  Soils  are  classed,  according  to  their  mode  of 
origin,  as  residual  and  transported. 

Residual  Soils  are  those  formed  by  rock  weathering  (see 
Residual  Clay,  under  Clay,  Chapter  IV),  and  are  found 
resting  on  the  parent  rock  from  whose  decay  they  have 
originated;  they  consequently,  in  most  instances,  show  a 
gradual  transition  from  the  surface  soil  to  the  solid  rock 
beneath.  Such  soils  are  often  of  great  extent  in  the 
unglaciated  areas  of  the  South,  and  their  clayey  character 
and  brilliant  coloring  is  a  marked  feature. 

With  this  class  there  is  sometimes  grouped  the  humus,  or 
peaty  soil,  formed  by  the  accumulation  of  vegetable  matter 
in  bogs  or  swamps  (see  Peat,  under  Coal,  Chapter  I). 

Transported  Soils. — The  materials  of  residual  areas  are 
frequently  carried  away  by  the  agency  of  water,  ice,  or  wind 
and  deposited  elsewhere,  commonly  at  lower  levels,  giving 
rise  to  transported  soils.  These  are  classified  either  accord- 
ing to  their  mode  of  origin  or  texture. 
213 


214          ECONOMIC  GEOLOGY   OF   THE   UNITED   STATES 

The  former  grouping  recognizes :  Alluvial  soils,  deposited  by  water  on 
the  lowlands  bordering  rivers  or  on  their  deltas ;  these  form  one  of  the 
most  important  soil  types,  and  the  fertile  soils  of  the  Nile  Valley  and  the 
Mississippi  bottoms  are  of  this  character.  Their  continued  high  fertility 
is  due  to  the  fact  that  the  soil  layer  is  added  to  annually  or  of tener  during 
periods  of  flood.  Glacial  drift  soils,  representing  the  debris  of  decayed 
rocks  of  various  kinds  brought  down  from  the  north  during  the  glacial 
period.  They  are  made  up  of  a  mixture  of  many  different  rock  types  in 
all  stages  of  decay;  the  continual  decomposition  of  their  component  min- 
eral grains  gives  them  a  more  or  less  permanent  fertility.  sEolian  soils, 
or  those  formed  by  wind  action,  include  :  (1)  Sand  dunes  heaped  up  by 
the  action  of  wind  along  the  shores  of  many  oceans  or  inland  seas. 
When  anchored  by  systematic  planting,  they  develop  an  abundant  plant 
growth.  (2)  Ash  soils,  representing  the  accumulations  of  ash  thrown 
out  over  a  region  during  outbursts  of  volcanic  activity ;  these  are  some- 
times of  high  productivity,  for  although  at  first  barren  and  sandy  they 
rapidly  decompose  to  a  good  soil. 

Properties  of  Soils.  —  The  productivity  of  a  soil  depends 
largely  on  its  chemical  and  physical  properties,  and  to  a 
lesser  extent  on  climatic  conditions. 

Chemical  Properties.  —  The  chemical  analysis  of  a  soil 
shows  a  variable  percentage  of  nitrogen,  silica,  phosphoric 
acid,  chlorine,  alumina,  lime,  magnesia,  iron  oxide,  potash, 
and  soda,  all  of  which,  with  the  exception  of  the  first,  are 
derivable  from  mineral  grains  present  in  the  soil.  When 
there  is  a  deficiency  of  any  one  of  these,  it  is  commonly 
remedied  by  adding  fertilizers  to  the  soil;  but  the  value  of 
the  latter  for  plant  maintenance  depends  not  so  much  on  the 
total  quantity  of  each  of  these  present,  but  upon  the  amount 
existing  in  soluble  form.  While  soils  vary  in  their  composi- 
tion from  place  to  place,  there  is  a  most  marked  difference 
between  the  soils  of  humid  and  arid  regions,  those  of  the 
latter  showing  a  much  larger  proportion  of  fertilizing  con- 


SOILS  215 

stituents  because  they  have  been  subjected  to  less  leaching 
action  by  rain  water.  Soils  in  arid  regions  are  often  covered 
by  a  whitish  crust  termed  "  alkali"  which  is  composed  chiefly 
of  sulphates  and  carbonates  of  soda,  and  is  formed  by  the 
soil  water  bringing  these  to  the  surface,  where  it  escapes  by 
evaporation.  An  excess  of  alkali  is  injurious  to  plants. 

Physical  Properties,  which  are  of  equal  importance  to  the 
chemical  ones,  include  texture,  structure,  color,  weight,  and 
temperature ;  a  proper  physical  condition  may  often  make 
up  for  a  deficiency  in  plant  food.  The  physical  characters 
of  a  soil  are  produced  to  a  large  extent  by  natural  processes, 
and  can  be  modified  but  slightly  by  man. 

The  texture  of  a  soil  refers  to  the  size  of  its  grains,  those 
recognized  being  clay,  silt,  sand,  and  gravel;  depending  on 
the  amount  of  each  of  these  present,  we  have  clay  soils,  silt 
soils,  loams,  sandy  soils,  and  gravelly  soils.  Texture  is  of 
importance  because  it  affects  the  retentive  power  of  the  soil 
for  moisture  and  gases.  Clay  soils  hold  much  water  and 
hence  are  wet  and  cold,  whereas  sandy  soils,  on  account  of 
the  coarseness  of  their  particles,  have  large  pores  and  hold 
little  water,  and  warm  up  easily.  Loamy  soils  stand  inter- 
mediate between  these. 

The  structure  of  the  soil  refers  to  the  arrangement  of  the 
particles.  If  compacted,  the  pores  are  small  and  the  soil 
holds  more  water,  while  if  loose  the  soil  behaves  like  sand, 
retaining  little  moisture.  A  puddled  soil  is  one  in  which 
the  grains  are  single,  while  in  a  flocculated  soil  the  particles 
are  bunched  together,  forming  compound  grains,  and  all  good 
soils  show  this  structure ;  it  increases  the  pore  space  and 
hence  facilitates  the  circulation  of  air  and  water  through  the 
mass.  Lime  encourages  flocculation. 


216          ECONOMIC   GEOLOGY   OF   THE   UNITED   STATES 

The  temperature  of  soils  depends  on  their  color  and 
position  with  relation  to  the  sun's  rays. 

In  moist  climates  the  clay  particles  are  washed  out  of  the 
upper  layers  of  the  soil  and  settle  in  the  lower  ones,  produc- 
ing a  differentiation  known  as  soil  and  subsoil.  This  is  not 
found  in  arid  regions. 

Distribution  of  Soils  in  the  United  States.  —  So  varied  are 
the  soils  of  the  United  States  that  it  would  require  many 
pages  to  describe  them  even  partially  ;  nevertheless,  there 
are  a  few  well-marked  types  underlying  extensive  areas 
which  may  be  briefly  referred  to.  The  residual  soils  occupy 
a  large  area  throughout  the  southern  states,  and  in  the 
Appalachian  belt  are  especially  prominent,  being  easily  recog- 
nized by  their  clayey  character  and  bright  colors.  Glacial 
soils  are  prominent  in  the  northern  United  States,  and  their 
high  fertility  has  been  noted  by  various  writers.  The  alluvial 
soils  are  prominent  in  all  parts  of  the  country.  In  the  cen- 
tral states  the  prairie  soil  is  a  peculiar  silty  type,  heavily 
impregnated  with  humus.  The  loess  is  a  silty  soil,  low  in 
organic  matter,  covering  many  square  miles  of  the  Great 
Plains,  and  needs  but  irrigation  to  make  it  blossom  with  har- 
vests. Marsh  soils  and  dune  soils  both  cover  many  thousands 
of  acres  along  the  Atlantic  coast ;  and  the  latter  are  also  ex- 
tensive around  the  Great  Lakes  as  well  as  along  the  Pacific 
coast.  Although  reclaimable  they  are  rarely  cultivated. 

REFERENCES  ON  SOILS 

Hilgard,  U.  S.  Dept.  Agric.,  Weather  Bur.,  Bull.  3,  1892  (Relations  of 
Soil  to  Climate) ;  King,  The  Soil,  Wiley  &  Sons  (New  York,  1898) ; 
Merrill,  Rocks,  Rock  Weathering,  and  Soils,  Macinillan  Co.  (New 
York,  1897);  Kamann,  Forstliche  Boden-kunde  und  Standortslehre 


SOILS  217 

(Berlin,  1897)  ;  Shaler,  U.  S.  Geol.  Surv.,  12th  Ann.  Kept.,  1 :  213, 
1891  (Origin  and  Nature)  ;  Warrington,  Physical  Properties  of  Soils 
(Oxford,  Eng.,  1900).  See  also  bulletins  U.  S.  Dept.  Agric.,  Bur.  of 
Soils,  especially  Nos.  4,  10,  15,  17,  18,  19,  22,  and  the  Reports  on 
Field  Operations  published  annually. 


ROAD    MATERIALS 

Under  this  term  are  included  clay,  sand,  gravel,  and  differ- 
ent kinds  of  consolidated  rock,  used  for  covering  the  surface 
of  a  highway.  In  former  years  but  little  consideration  was 
given  to  the  proper  selection  of  these  materials,  but  now 
the  subject  is  receiving  an  increasing  amount  of  attention 
from  engineers,  with  the  results  that  certain  required 
standards  have  been  set  up,  and  in  many  localities  carefully 
adhered  to.  Such  standards  can  however  be  applied  only 
to  consolidated  materials. 

In  many  parts  of  the  United  States  the  roads  have  natural 
beds,  whose  character  depends  on  that  of  the  local  formations. 
The  road,  therefore,  may  consist  of  clay,  sand,  loam,  gravel, 
or  bare  rock,  and  such  a  road  surface  is  unfortunately  used 
even  when  better  materials  are  at  hand,  but  are  overlooked 
through  indifference  or  ignorance. 

Clay  makes  a  hard  road  in  dry  weather,  but  becomes  very 
sticky  in  wet,  or  even  dusty  after  prolonged  drought.  Sand 
packs  well  if  wet,  but  makes  hard  pulling  when  dry.  Gravel, 
if  ferruginous,  will  often  cement  to  a  good  road  surface, 
which  wears  well  under  light  traffic.  Shale  will  also  make 
a  good  road.  Natural  road  beds  are,  however,  unsatisfactory 
at  best,  and  artificial  ones  of  crushed  stone  (macadam  roads) 
are  rapidly  superseding  them. 

For  this  purpose  a  number  of  different  kinds  of  rock  are 


218         ECONOMIC   GEOLOGY   OF   THE   UNITED   STATES 

employed,  including  trap,  granite,  limestone,  dolomite,  and 
sandstone. 

The  essential  qualities  of  a  stone  for  macadamizing  are  : 
(1)  Hardness  to  resist  crushing  under  traffic.  (2)  Sufficient 
abrasion  to  permit  the  formation  of  some  dust  which  when 
moistened  will  form  a  cement  to  bind  the  particles  together. 
(3)  Freshness  of  the  mineral  grains.  (4)  Cheapness.  Great 
variation  is  found  to  exist  among  the  different  stones  with 
respect  to  these  requirements,  and  even  stones  of  the  same 
kind  lack  uniformity. 

While  the  most  practical  test  for  road  material  is  actual 
use,  this  is  not  always  a  cheap  or  rapid  method,  and  conse- 
quently a  series  of  physical  tests  has  been  adopted,  which 
is  in  use  in  most  highway  laboratories.  The  two  important 
tests  are  the  abrasive  test  and  impact  test.  In  the  former 
the  abrasive  resistance  of  the  stone  is  determined,  in  the 
latter  the  cementing  power  of  the  powdered  stone  is  meas- 
ured, by  forming  it  into  briquettes,  which  are  broken  by  a 
series  of  blows.  The  same  powder  is  remolded  and  again 
broken  to  determine  its  recementing  power.  Stones  with  a 
small  amount  of  argillaceous  and  calcareous  impurities  often 
appear  to  have  good  cementing  power  ;  but  in  every  case  the 
qualities  of  each  stone  have  to  be  determined  separately. 

Since,  however,  stone  for  road  building  will  not  bear  the 
cost  of  long  transportation,  it  becomes  necessary  to  make  a 
careful  selection  of  the  best  that  the  vicinity  affords.  Trap 
rock  and  hard  argillaceous  limestone  are  perhaps  more  used 
than  any  other  materials. 

Good  stones  for  road  building  are  more  or  less  widely 
distributed  in  most  parts  of  the  United  States,  so  that  any 
detailed  mention  of  localities  is  not  needed. 


SOILS  219 

REFERENCES  ON  ROAD  MATERIALS 

Merrill,  N.  Y.  State  Museum,  Bull.  17,  1897  (N.  Y.) ;  Reid  and  Johnson, 
Md.  Geol.  Surv.,  I  and  IV;  Shaler,  U.  S.  Geol.  Surv.,  16th  Ann. 
Kept.,  II :  227,  1895  (Mass.).  See  also  bulletins  issued  by  Highway 
Division  of  Dept.  of  Agric.,  Wash.,  and  Reports  of  Massachusetts 
Highway  Commission. 


PART   II 

METALLIC   MINERALS 


CHAPTER  XIII 
ORE  DEPOSITS 

Definition.  —  The  term  ore  deposits  is  applied  to  concen- 
trations of  economically  valuable  metalliferous  minerals 
found  in  the  earth's  crust,  while  under  the  term  ore  are 
included  those  portions  of  the  ore  body  of  which  the  metallic 
minerals  form  a  sufficiently  large  proportion  to  make  their 
extraction  profitable.  A  metalliferous  mineral  or  rock 
might  therefore  not  be  an  ore  at  the  present  day,  but 
become  so  at  a  later  date,  because  improved  methods  of 
treatment  or  other  conditions  rendered  the  extraction  of 
its  metallic  contents  profitable. 

A  few  metallic  minerals  serving  as  ores,  such  as  gold, 
copper,  platinum,  or  mercury,  sometimes  occur  in  a  native 
condition ;  but  in  most  cases  the  metal  is  combined  with 
other  elements,  forming  sulphides,  hydrous  oxides,  carbon- 
ates, sulphates,  silicates,  chlorides,  phosphates,  or  rarer 
compounds,  the  first  five  of  these  being  the  most  numer- 
ous. A  deposit  may  contain  the  ores  of  one  or  several 
metals,  and  there  may  also  be  several  compounds  of  the 
same  metal  present. 

Gangue  Minerals.  —  Associated  with  the  metallic  minerals 
there  are  usually  certain  common  non-metallic  ones  which 
carry  no  values  worth  extracting.  These  are  termed  the 
gangue  minerals.  They  often  form  masses  in  the  ore  deposit 


224          ECONOMIC   GEOLOGY  OF  THE   UNITED   STATES 

which  can  be  avoided  or  thrown  out  in  mining,  but  at  other 
times  they  are  so  intermixed  with  the  valuable  metalliferous 
minerals  that  the  ore  is  crushed  and  the  two  separated  by 
special  methods. 

Quartz  is  the  most  abundant  gangue  mineral,  but  calcite, 
barite,  fluorite,  and  siderite  are  also  common,  while  dolo- 
mite, hornblende,  pyroxene,  feldspar,  rhodochrosite,  etc.,  are 
found  in  some  ore  bodies. 

Origin  of  Ore  Bodies.  —  The  fact  that  ores  form  masses 
of  greater  or  less  concentration  is  explainable  in  two  ways : 
either  they  have  been  formed  contemporaneously  with  the 
inclosing  rock;  or  else  they  have  been  formed  by  a  process 
of  concentration  at  a  later  date.  The  first  theory  is  found 
to  be  applicable  to  some  ores  in  igneous  rocks,  and  probably 
some  sedimentary  ones,  while  the  second  applies  to  most  ore 
deposits  regardless  of  the  character  of  the  inclosing  rock. 

Ores  of  Contemporaneous  Origin.  —  If  the  ore  in  an  igneous 
rock  were  formed  at  the  same  time  as  the  rock,  it  would 
indicate  a  crystallization  of  metallic  minerals  from  the 
igneous  magma  during  cooling ;  and  this,  in  some  cases,  is 
true,  it  being  found  that  the  metallic  elements  in  many 
basic  rocks  tend  to  segregate  during  cooling,  sometimes 
forming  masses  of  considerable  size  and  of  high  purity. 
This  mode  of  origin,  termed  magmatic  segregation  (18,  34,  35,^ 
36),  was  shown  by  Vogt  to  apply  to  the  titaniferous  ores  of 
Scandinavia;  and  although  the  importance  of  the  theory 
was  not  at  first  generally  appreciated  in  America,  where 
deposits  of  this  type  are  rare,  still  it  is  now  generally 
accepted.  The  best-known  American  examples  of  this 
class  are  the  titaniferous  magnetites  and  the  chromite  ores. 


ORE   DEPOSITS  225 

Spurr  has  suggested  (34)  that  certain  ores  found  in  acid 
rocks,  such  as  quartz  veins,  have  also  been  formed  by  mag- 
matic  segregation.  He  believes  that  siliceous  rocks,  such 
as  granites,  may  originate  by  differentiation  from  a  more 
basic  magma.  A  further  development  of  this  process 
yields  quartz -feldspar  rocks,  and  after  the  minerals  of 
these  have  crystallized  out,  only  pure  silica  is  left,  which 
forms  quartz  veins.  Examples  of  this  type  have  been 
noted  by  Spurr  from  Alaska,  and  by  Turner  from  Silver 
Peak,  Nevada. 

If  ores  in  sedimentary  rocks  are  of  contemporaneous 
origin,  then  the  deposit  must  be  a  bedded  one  conforming 
to  the  stratification  of  the  rock,  and  this  explanation  more- 
over requires  the  presence  of  metalliferous  minerals  in  and 
their  deposition  from  sea  water.  While  certain  metallic 
elements  are  found  in  the  waters  of  the  ocean,  their  quan- 
tity is  extremely  small  and  not  to  be  compared  with  what 
may  be  found  in  disseminated  or  concentrated  form  in 
sedimentary  and  igneous  rocks.  It  has  been  shown,  how- 
ever, that  some  metallic  minerals,  such  as  limonite,  pyrite, 
or  manganese,  are  occasionally  precipitated  on  the  ocean 
floor.  While  economic  geologists  have  assigned  a  contem- 
poraneous origin  to  certain  ores  found  in  sedimentary  strata, 
and  in  certain  instances  their  theories  have  been  quite 
generally  regarded  as  correct  (iron  ores,  ref.  36),  still  the 
majority  at  the  present  day  believe  that  most  ore  deposits 
are  of  later  date  than  the  inclosing  rock,  and  must  have 
been  formed  by  a  process  of  concentration,  aided  in  the 
majority  of  cases  by  circulating  water. 

Concentration  of  Ores  in  Rocks.  —  In  order  to  demonstrate 
this,  it  is  necessary  to  show:  (1)  the  presence  of  disseminated 


226    ECONOMIC  GEOLOGY  OF  THE  UNITED  STATES 

minerals  in  the  earth's  crust ;  (2)  the  existence  of  a  solvent 
or  carrier;  and  (3)  the  presence  in  most  cases  of  cavities 
in  which  the  precipitation  of  the  ore  can  occur. 

It  is  well  known  that  metallic  minerals  in  small  quanti- 
ties are  widely  distributed,  in  both  igneous  and  sedimentary 
rocks.  Sandberger  (31),  for  example,  has  shown  by  analyses 
the  presence  of  nickel,  copper,  lead,  tin,  and  cobalt  in  such 
minerals  as  hornblende,  olivine,  and  mica ;  and  Curtis  has 
found  traces  of  silver,  gold,  and  lead  in  the  quartz-porphy- 
ries at  Eureka,  Nevada  (U.  S.  Geol.  Surv.,  Mon.  VII :  80), 
and  silver,  arsenic,  lead,  copper,  gold,  and  silver  in  the 
granite  at  Steamboat  Springs,  Nevada  (U.  S.  Geol.  Surv., 
Mon.  XIII :  350).  Winslow  has  pointed  out  the  presence 
of  small  quantities  of  lead  and  zinc  in  the  limestones  of 
Missouri  and  Wisconsin  (lead  and  zinc,  ref.  17),  and 
Wagoner  has  made  similar  tests  on  California  sediments 
(42).  Since,  however,  the  sediments  were  originally  derived 
from  the  igneous  rocks,  it  follows  that  the  latter  must  be 
the  original  source  of  the  minerals.  It  is  interesting  to 
note  that  even  in  the  igneous  rocks  the  metals  are  not 
impartially  distributed,  but  that  certain  metals  seem  to 
favor  certain  rocks  (De  Launay,  Ann.  d.  Min.,  August, 
1897,  and  ref.  34).  Tin  seems  to  favor  granite,  and  chro- 
rnite,  peridotite. 

As  regards  the  second  point,  it  is  now  generally  admitted 
that  water  is  an  important  agent  in  the  concentration  of 
many  ores.  While  cold  water,  free  from  impurities,  has 
comparatively  little  solvent  power,  the  presence  of  acids  or 
alkalies  materially  increases  its  capacity  for  solution,  and 
heat  and  pressure  have  also  a  great  influence.  Analyses  of 
mine,  spring,  and  surface  waters  have  shown  the  presence 


ORE   DEPOSITS 


227 


of  many  dissolved  alkalies  and  other  salts  (24),  and  occa- 
sionally small  quantities  of  metals. 

The  following  two  analyses,  which  will  serve  as  examples, 
give  the  calculated  composition  of  (1)  vadose,  or  shallow 
water,  from  the  500-foot  level  of  the  Geyser  silver  mine, 
Silver  Cliff,  Colorado,  and  (2)  deep  water  from  the  2000- 
foot  level  of  the  same  mine.  The  ore  occurs  in  rhyolite. 
The  figures  are  grams  per  1000  liters:  — 


SiOa 25.90 

A1203 

A1203,PA      . 

FeC03 1.50 

MnCOg 1.70 

CaC03 93.50 

Ca3P208 

CaF2 

SrCO3 

MgC03 42.85 

K2SO4 4.20 

KCL 16.60 

KBr,  KI 

Na3CO3 38.70 

Na2SO4 60.50 

NaNO3 

Na2B407 

LiCl 

CO, 37.20 

PbCO3 Tr 

CuC03 Tr 

ZnCO3 .40 


24.42 
1.06 


7.25 
1.19 


Tr 

Tr 

3.29 

621.84 

19.18 

361.34 

Tr 

1489.67 

223.53 

2.19 

Tr 

17.30 

1418.61 

1.74 

.04 


The  higher  percentage  of  dissolved  substances  in  the  deep 
water  is  quite  marked. 

While  the  importance  of  hot  waters  as  an  agent  in  the 


228          ECONOMIC   GEOLOGY  OF   THE   UNITED  STATES 

formation  of  ore  deposits  is  clearly  recognized  by  many,  and 
traces  of  metals  in  solution  are  sometimes  found,  still  ex- 
amples of  such  deposits  now  forming  are  rare.  Weed  has 
described  a  hot  spring  near  Boulder,  Montana  (49),  which  is 
depositing  auriferous  quartz,  and  the  deposit  is  pointed  out 
by  him  to  be  identical  with  silver  and  gold  bearing  quartz 
veins  of  the  region  between  Butte  and  Helena,  Montana.  At 
Steamboat  Springs,  Nevada,  it  has  been  found  that  the  allu- 
vial gravels  underlying  the  hot  spring  sinters  are  cemented 
by  stibnite  and  pyrite  (Lindgren,  Amer.  Inst.  Min.  Eng., 
Trans.  1905  :  275).  Of  still  more  interest  is  the  collection 
by  evaporation  of  copper  from  certain  Javan  hot  springs, 
in  which  the  metal  occurs  as  iodide  of  copper  (Stevens, 
Copper  Handbook,  IV :  156,  1904). 

Water  is  known  to  be  widely  (11,  39)  but  not  uniformly 
distributed  in  the  rocks  of  the  earth's  crust,  and  much  of  it 
is  in  slow  but  constant  circulation.  While  it  is  admitted  by 
most  geologists  that  this  water  has  been  an  important  ore 
carrier,  collecting  the  disseminated  metals  in  the  rocks  and 
concentrating  them  in  localities  favorable  to  deposition, 
still,  there  exists  a  difference  of  opinion  regarding  its 
source,  one  class  maintaining  that  it  is  largely  of  meteoric 
origin,  the  other  that  it  is  derived  chiefly  from  igneous 
intrusions. 

The  chief  exponent  of  the  former  theory  is  Van  Hise,  who 
points  out  that  the  earth's  crust  may  be  divided  into  three 
zones  :  (1)  an  upper  zone  of  fracture,  beginning  at  the  sur- 
face ;  (2)  a  zone  of  combined  fracture  and  flowage  ;  and 
(3)  a  zone  of  rock  flowage,  or  of  no  fracture.  In  the  zone 
of  no  fracture  the  pressure  is  so  great  that  any  dynamic 
disturbances  will  cause  flowage  instead  of  fracturing,  and  no 


ORE  DEPOSITS  229 

cavities  of  appreciable  size  can  exist.  The  depth  of  this  zone 
will  depend  on  the  kind  of  rock,  Van  Hise  having  figured 
that  cavities  probably  cannot  exist  in  soft  shales  at  depths 
below  1625  feet  (500  meters),  and  in  firm  granites  below 
32,500  ft.  (10,000  meters). 

Into  this  zone  of  no  fracture,  water  from  the  surface  can- 
not penetrate,  but  above  it  there  may  be  active  percolation 
by  water.  It  is  well  known  that  rain  water,  falling  on  the 
earth's  surface,  seeps  through  the  soil  into  the  underlying 
rocks,  permeating  them  to  a  variable  depth,  and  forming  a 
more  or  less  saturated  zone,  whose  upper  limit,  lying  at  a 
variable  depth,  is  known  as  the  ground- water  level.  In 
this  zone  of  more  or  less  complete  saturation  there  is  a  slow 
but  continual  circulation,  from  areas  of  high  to  areas  of  low 
pressure,  along  irregular  winding  routes,  often  leading  back 
to  the  surface  and  giving  rise  to  springs.  According  to 
Van  Hise  this  percolating  meteoric  water  obtains  its  load  of 
metallic  elements  from  the  rocks,  which  it  traverses  in  its 
passage  through  the  zone  of  fracture,  depositing  some  of  it 
in  the  trunk  channels,  but  being  incapable  of  entering  the 
zone  of  no  fracture. 

The  opponents  (6,  18,  20,  21)  of  Van  Hise's  theory  point 
to  the  following  facts  as  evidence  that  waters  of  igneous 
origin  are  more  important  as  ore  carriers,  and  are  the 
ones  involved  in  deep  circulation.  Meteoric  waters  do 
not  reach  great  depths,  in  fact  probably  not  more  than 
2000  feet  or  sometimes  less  from  the  surface,  and  when 
they  do  penetrate  to  a  greater  distance  from  it,  it  is  be- 
cause they  have  followed  some  fissure.  The  lower  levels 
of  many  deep  mines  are  so  dry  as  to  be  dusty.  Ores  have 
been  concentrated  at  a  much  greater  depth  than  that  reached 


230          ECONOMIC   GEOLOGY  OF   THE  UNITED   STATES 

by  surface  waters.  It  is  perfectly  reasonable  to  regard 
igneous  rocks  as  an  important  source  of  water,  and  the 
experiments  of  Daubree  have  shown  that  a  molten  granite 
contains  a  large  amount  of  water  vapor  which  it  retains 
while  at  great  depths,  but  gives  off  on  approaching  the 
surface  and  cooling.  While  the  temperature  and  pressure 
are  still  high  this  water  escapes  as  vapor,  and  later,  with 
decrease  in  temperature  and  pressure,  as  a  liquid.  Under 
favorable  conditions  this  water  may  force  itself  upwards 
aud  finally  mingle  with  meteoric  waters,  carrying  metals 
obtained  both  from  the  liberated  waters  and,  to  a  less  extent, 
from  the  leaching  of  cooled  igneous  rock. 

It  is  an  undeniable  fact  that  most  metalliferous  veins  are 
found  in  areas  of  igneous  rocks,  and  Lindgren  (see  refer- 
-ences  on  gold,  79)  has  shown  that  in  the  case  of  the  gold  de- 
posits of  North  America  the  periods  of  vein  formation  agreed 
closely  with  those  of  igneous  activity.  It  is  also  a  noteworthy 
fact  that,  with  the  exception  of  the  deposits  of  commoner 
metals,  such  as  iron,  and  some  copper,  lead,  and  zinc,  ores 
are  found  in  close  association  with  igneous  intrusions,  which 
seems  to  postulate  a  close  connection  between  igneous  rocks 
and  ore  deposits,  as  advocated  by  such  authorities  as  Weed, 
Kemp,  Lindgren,  and  Emmons;  and  although  opposed  by 
Van  Hise,  it  is  now  held  by  many  economic  geologists  that 
most  metalliferous  deposits,  aside  from  ores  of  iron,  have 
resulted  by  deposition  from  ascending  waters  in  regions  of 
igneous  intrusions,  the  waters  being  probably  in  large  part 
at  least  of  igneous  origin.  This  much  should  be  said.  The 
metalliferous  minerals  as  originally  deposited  have  not 
always  been  sufficiently  concentrated  to  serve  as  ores,  but 
they  have  become  concentrated  at  a  later  date  by  meteoric 


ORE   DEPOSITS  231 

waters,  as  at  Bisbee,  Arizona.  (See  Ransome,  under  copper 
references.)  Posepny  (24),  in  his  work  on  the  Genesis  of 
Ore  Deposits,  distinguishes  between  descending  surface 
waters,  or  vadose  circulations,  and  ascending  waters  from 
great  depths.  It  is  the  former  that  have  been  active  in 
the  secondary  concentration  of  ores. 

Formation  of  Cavities.  —  The  deposition  of  ores  in  the 
rocks  is  greatly  facilitated  by  the  presence  of  cavities  along 
which  the  ore-bearing  solutions  freely  pass,  and  consequently 
a  great  many  ore  deposits  occur  in  such  spaces.  There  are 
a  number  of  different  ways  in  which  cavities  may  be  formed 
in  rocks.  The  percolation  of  surface  water  through  certain 
ones,  such  as  limestones,  often  results  in  the  formation  of 
solution  cavities,  these  in  many  instances  attaining  the  size 
of  veritable  caverns  ;  a  soluble  rock  may  contain  more  or 
less  insoluble  material,  such  as  clay  or  chert,  which  collapses 
when  the  surrounding  rock  is  dissolved,  and  partly  fills  the 
cave  thus  formed.  At  times  the  more  resistant  parts  are  so 
bound  together  that  they  remain  in  their  original  position, 
forming  a  porous  mass,  in  the  cavities  of  which  mineral 
matter  is  later  deposited. 

Dynamic  disturbances  produce  cavities  of  variable  extent 
in  many  different  rocks.  These  range  from  microscopic 
cracks,  like  the  rift  planes  of  granite,  to  enormous  faults 
of  great  depth  and  linear  extent,  and  include  the  joint 
planes  so  common  in  the  rocks  of  almost  all  regions.  Fault 
fissures  form  one  of  the  most  important  types  of  passage- 
ways for  ore-bearing  solutions.  They  are  often  irregular, 
branching,  and  partly  filled  by  fault  breccia,  caused  by  the 
breaking  of  the  rock  during  the  movement  along  the  fault 
plane.  A  third  important  group  of  cavities  in  the  rocks  are 


232          ECONOMIC   GEOLOGY  OF  THE   UNITED   STATES 

those  resulting  from  shrinkage  of  the  mass,  which  may  be 
due  to  (1)  shrinkage  during  cooling,  as  in  igneous  rocks ; 
(2)  shrinkage  during  certain  forms  of  replacement.  For 
example,  the  change  of  carbonate  of  lime  to  dolomite  is 
accompanied  by  a  shrinkage  of  the  mass,  which  renders  the 
dolomite  more  porous  than  the  original  rock;  and  in  the 
alteration  of  siderite  to  limonite  there  is  a  shrinkage  of 
fully  20  per  cent  (25).  A  fourth  type  of  channel  way  for  the 
passage  of  underground  water  is  the  contact  plane  between 
two  quite  different  kinds  of  rock,  one  of  them  fairly  dense 
and  impervious  ;  for  example,  the  contact  plane  between  a 
granite  mass  and  a  series  of  sedimentary  strata. 

Precipitation  of  Metals  from  Solution.  —  The  conditions 
which  increase  the  solvent  power  of  water  have  already  been 
referred  to.  To  this  should  be  added  the  statement  that 
solution  generally  takes  place  out  of  contact  with  the  air. 

When  the  ore-bearing  solutions  approach  the  surface  or 
enter  a  cavity,  the  load  of  dissolved  minerals  is  deposited 
wholly  or  in  part,  due  to  cooling  of  the  solution,  release  of 
pressure,  or  by  oxidation,  which  converts  certain  soluble 
salts  into  an  insoluble  form.  Chemical  reactions  between 
two  different  solutions  meeting  in  a  cavity  or  at  the  inter- 
section of  fissures  may  also  cause  precipitation.  Iron  com- 
pounds, for  example,  may  go  into  solution  in  the  form  of 
carbonate,  but  on  exposure  to  the  air  the  latter  is  rapidly 
changed  to  limonite,  which  is  insoluble. 

While  the  deposition  of  the  ore  often  takes  place  in  cavi- 
ties below  the  surface,  there  are  cases  in  which  it  is  not 
precipitated  until  it  reaches  the  surface,  as  in  a  pond  or  in 
the  soil.  Certain  special  conditions  of  deposition  should 
also  be  noted. 


ORE   DEPOSITS  233 

Replacement  or  Metasomatism  (22).  —  It  is  a  well-known 
fact  that  under  favorable  conditions  mineral-bearing  solu- 
tions may  attack  the  minerals  of  the  rocks  which  they  pene- 
trate, dissolving  them  wholly  or  in  part,  and  depositing 
some  of  the  original  burden  in  place  of  the  material  re- 
moved. This  replacement,  termed  "metasomatism,"  is  an 
important  factor  in  the  formation  of  many  ore  deposits,  and 
may  involve  a  total  or  partial  loss  of  certain  constituents  of 
the  rock  attacked  and  a  gain  of  others,  even  to  the  extent 
of  introduction  of  entirely  new  compounds  and  elements. 
The  change  takes  place  molecule  by  molecule,  a  grain  of 
vein  material  being  deposited  for  each  grain  of  replaced 
rock  dissolved.  The '  ore-bearing  solutions  penetrate  the 
rock  first  along  the  smallest  cracks,  and  then  work  their 
way  into  the  individual  mineral  grains  along  their  cleavage 
planes,  until  they  finally  permeate  the  entire  mass. 

Metasomatic  processes  show  great  variety,  and  are  not 
confined  to  one  kind  of  rock  or  mineral.  In  its  simplest 
form  the  result  of  metasomatism  may  often  be  seen  in  fossil- 
iferous  rocks,  where  organic  remains  have  been  replaced  by 
common  mineral  compounds,  as  in  the  replacement  of  the 
lime  carbonate  of  corals  by  quartz,  or  the  replacement  of 
molluscan  shells  by  pyrite.  From  such  simple  conditions 
there  is  every  gradation  to  the  complete  replacement  of 
extensive  areas  of  rock  by  ore,  or  to  the  extensive  operation 
of  metasomatism  along  the  walls  of  fissure  veins.  In  most 
cases  the  changes  are  believed  to  be  due  to  the  action  of 
underground  water ;  but  in  some  instances  it  seems  probable 
that  the  processes  of  pneumatolysis  (see  below)  were  in- 
volved. Moreover,  high  temperature,  pressure,  and  concen- 
tration seem  to  have  been  present  in  replacement,  especially 


234 


ECONOMIC   GEOLOGY   OF  THE   UNITED  STATES 


in  the  case  of  ore  deposits  in  fissure  veins.  It  is  rarely 
possible,  without  examination  of  a  thin  section  with  the 
microscope,  to  decide  whether  minerals  present  are  due  to 
replacement  or  to  simple  interstitial  filling.  Fig.  37  shows 
a  replacement  vein  in  syenite. 

Some  minerals  are  more  easily  replaceable  than  others, 
consequently  the  rocks  in  which  such  predominate  might 

be  more  widely  affected  than 
others.  (See  Butte,  Mon- 
tana, and  Clifton,  Arizona, 
under  Copper.) 

The  theory  of  metasoma- 
tism was  first  applied  in 
America  by  Pumpelly  in 
1871,  in  explanation  of  the 
copper  deposits  of  Michigan; 
but  the  ore  bodies  of  Lead- 

FIG.  37.  -Replacement  vein  in  Syenite      viHe    Colorado,  and  Eureka, 
Rock,  War  Eagle  Mine,  Rossland, 

B.  c.    (a)  granular  orthociase  with     Nevada,  were  the  first  large 

a  little  sericite  ;  (b)  secondary  biotite  ;  . 

(q)  secondary  quartz  ;    (c)  chlorite  ;      deposits    whose     origin    was 

explained  by  it.  Since  then 
the  great  importance  of 
metasomatism  has  been  widely  recognized,  and  it  has  become 
evident  that  preexisting  cavities  are  not  necessary  to  the 
formation  of  ore  bodies. 

Concentration  by  Eruptive  After-action  (45)  (Pneumatolysis*). 
—  The  term  pneumatolysis  was  first  used  by  Bunsen  to 
describe  the  combined  action  of  gases  and  water.  This 
assumes  that  during  cooling  many  magmas  give  off  watery 
vapor,  heated  above  its  critical  temperature  (365°  C.)  and 
under  high  pressure.  With  this  there  are  also  mineralizing 


ORE   DEPOSITS  235 

vapors  and  metals,  combined  to  form  volatile  compounds. 
These  materials,  together  with  any  other  elements  given  off, 
may  then  be  deposited  either  at  the  contact  between  the 
intrusive  and  the  surrounding  rocks,  forming  a  true  contact 
deposit,  or,  as  in  the  case  of  the  tin  veins  of  Cornwall,  Eng- 
land, in  fissures  formed  in  the  surrounding  rocks  by  the 
intrusions.  Though  the  great  importance  of  this  class  of 
ore  deposits  has  been  but  recently  recognized,  it  is  now 
being  found  that  a  number  of  known  deposits  are  of  this 
origin.  They  are  usually  found  in  calcareous  rocks  at  or 
near  the  contact  with  granitic  intrusions.  The  ore  minerals 
are  specularite,  magnetite,  bornite,  chalcopyrite,  pyrite,  pyr- 
rhotite,  and  more  rarely  galena  and  blende;  while  asso- 
ciated with  them  are  characteristic  contact  minerals,  such 
as  epidote,  wollastonite,  garnet,  vesuvianite,  and  hematite. 
The  sulphides  sometimes  carry  gold  and  silver,  and  tellu- 
rides  are  not  rare  (51).  A  characteristic  feature,  however, 
is  the  association  of  iron  oxides  and  sulphides,  an  almost 
unknown  thing  in  fissure  veins.  Since  these  minerals  are 
sometimes  found  in  limestones  of  great  purity,  it  is  consid- 
ered as  quite  evident  that  in  such  cases,  at  least,  most  of  the 
foreign  matter  has  been  derived  from  the  igneous  mass. 
Examples  of  contact  deposits  are  South  Mountain,  Idaho, 
Seven  Devils  District,  Idaho,  and  Clifton,  Arizona  (in  part). 

Other  Causes  of  Precipitation.  —  Some  fifty  years  ago  not 
a  few  geologists,  prominent  among  them  De  la  Beche,  advo* 
cated  the  theory  of  ore  precipitation  by  galvanic  action  (1, 9), 
and  a  number  of  experiments  were  made  attempting  to  prove 
the  existence  of  such  action ;  now  little  weight  is  attached 
to  this  theory. 

More  recently  Gillette  (13)  has  expressed  the  view  that 


236          ECONOMIC    GEOLOGY    OF   THE   UNITED    STATES 

osmotic  pressure  is  an  important  factor  in  ore  deposition, 
aiding  to  spread  the  dissolved  metals  through  the  water  in 
the  rocks,  toward  centers  of  crystallization. 

Forms  of  Ore  Bodies.  —  Ore  bodies  vary  greatly  in  their 
form,  and  this  character  has  at  times  been  used  as  a  basis 
of  classification  by  some  writers ;  but  the  more  modern  tend- 
ency is  to  use  genetic  characters  instead,  making  form  of 
secondary  importance  in  the  grouping.  Certain  forms  of 
ore  bodies  are  so  numerous  as  to  deserve  special  mention. 

Fissure  Veins  (8,  12,  16,  29,  47). —  A  fissure  vein  may  be 
defined  (22)  as  a  tabular  mineral  mass  occupying  or  closely 
associated  with  a  fracture  or  set  of  fractures  in  the  inclosing 
rock,  and  formed  either  by  filling  of  the  fissures  as  well  as 
pores  in  the  wall  rock,  or  by  replacement  of  the  latter  (meta- 
somatism). When  the  vein  is  simply  the  result  of  fissure 
filling,  the  ore  and  gangue  minerals  are  often  deposited  in 
successive  layers  on  the  walls  of  the  fissure  (Rico,  Colorado), 
the  width  of  the  vein  depending  .on  the  width  of  the  fissure 
and  the  boundaries  of  the  ore  mass  being  sharp.  In  most 
cases,  however,  the  ore-bearing  solutions  have  entered  the 
wall  rock  and  either  filled  its  pores  or  replaced  it  to  some 
extent,  thus  giving  the  vein  an  indefinite  boundary.  There- 
fore the  width  of  the  fissures  does  not  necessarily  stand  in  any 
direct  relation  to  the  width  of  the  vein  (47)  (Butte,  Montana). 

Veins  formed  by  the  simple  filling  of  a  fissure  often  show 
a  banded  structure  of  varying  regularity  termed  (Trustification l 
by  Posepny  (Fig.  38),  which  may  sometimes  be  brecciated 
by  later  movements  along  the  fissure.  Secondary  bands 
may  be  formed  after  reopening  of  the  fissures  (Fig.  38), 
and  such  a  movement  may  cause  brecciation  of  the  vein 

1  The  replacement  of  certain  layers  only  in  a  bed  of  stratified  rock  may 
also  produce  a  banded  structure. 


ORE  DEPOSITS 


237 


material,  or  allow  the  ingress  of  the  weathering  agents 
which  decompose  the  wall  rock,  giving  rise  to  a  layer  of 
clay  known  as  selvage.  Where  the  fissure  has  not  been  com- 
pletely filled,  thus  leaving  a  central  space  into  which  the 
crystals  of  gangue 
project,  a  comb 
structure  is  formed. 
The  bands  in  a 
filled  fissure  may 
consist  of  gangue 
and  ore  alternat- 
ing, or  of  different 
ores.  Among  the 
commonest  ores 
seen  in  these  fis- 
sure veins  are  py- 
rite,  chalcopyrite, 
galena,  blende,  and 
sulphides  of  silver. 
Some  regions  af- 
ford especially  fine 
examples  of  banded 
veins,  notably  those 
of  Grass  Valley,  California,  and  Rico,  Colorado.  Abroad 
the  mines  of  Freiberg,  Saxony,  and  Clausthal,  Prussia,  also 
often  yield  magnificent  specimens.  Even  in  a  single  vein 
the  ore  may  follow  certain  streaks  which  are  termed  shutes, 
or  again  it  may  be  restricted  to  pockets  of  great  richness, 
which  are  known  as  bonanzas. 

Fissure  veins  in  which  metasomatic  action  has  predom- 
inated show  great  irregularity  of  width  and  an  absence  of 


FIG.  38.  —  Section  of  vein  in  Enterprise  mine,  Rico, 
Colo.  The  right  side  shows  later  banding  due  to 
reopening  of  the  fissure.  After  Ransome,  U.  S. 
Geol.  Surv.,  22d  Ann.  Kept.,  11 :  262. 


238 


ECONOMIC   GEOLOGY   OP  THE  UNITED   STATES 


well-defined  boundaries  ;  they  also  lack  as  a  rule  the  sym- 
metrical banding  and  the  breccias  cemented  by  vein  material. 
There  are  all  gradations  between  these  two  types  of  fissure 
veins;  and  even  in  a  single  vein,  simple  filling  may  occur 
in  one  part  and  replacement  in  another. 

Veins  often  split  (PI.  XX,  Fig.  2),  or  intersect,  and  at  the 
point  of  intersection  or  splitting  the  ore  is  apt  to  be  richer. 
There  are  other  reasons  for  variations  in  richness,  among 
the  most  important  being  the  character  of  the  wall  rocks, 
some  kinds  being  more  easily  replaceable  or  more  porous 
than  others.  Their  physical  character  will  moreover  exer- 
cise considerable  influence  on  the  shape  and  size  of  the 
fissure.  Tough  rocks  like  gneiss,  for  example,  give  a  clean- 

cut  fissure,  but  in  brittle  rock 
the  fissure  is  apt  to  split  fre- 
quently, and  therefore  a  vein 
may  be  workable  in  one  kind 
of  rock,  but  becomes  worth- 
less when  passing  to  another, 
since  the  profuse  branching 
interferes  with  economical 

.  .    . 

After  Beck,  Lehre  von  der  Erzla-      mining    (*  Ig.    39).      A    dike 
gerstatten:  135,  1901. 


FIG.  39.  —  Section  showing  change  in 
character  of  vein  passing  from 

gneiss  (</)  to  quartz  porphyry  (p). 


larities,  and  in  a  given  region  the  fissures  not  uncommonly 
show  great  variation  in  their  direction.  Thus  at  Butte, 
Montana,  east-west  veins  predominate  (Fig.  53),  while  in 
the  Silverton  district  of  Colorado  they  cut  the  rocks  in  all 
directions,  but  the  majority  show  a  north  of  east  trend.  In 
the  Monte  Cristo,  Washington,  district  the  veins  with  north- 
east trend  are  predominant  (Fig.  40). 

Fissure  veins  vary  considerably  in  their  width,  swelling 


ROBERT  W.  WEBB 

GEOLOGY  DEPT.,  U.C.LA. 


ORE   DEPOSITS 


239 


at  some  points  and  pinching  or  narrowing  at  others.  They 
also  at  times  show  lateral  enrichment ;  for  instance,  where 
the  ore  cuts  through  stratified  beds,  into  which  the  ore- 
bearing  solutions  have  spread  out  laterally  along  the  planes  of 
stratification  or  other 
planes.  It  has  been 
noticed  in  some  veins, 
especially  those  formed 
by  replacement,  that 
the  filling  varies  with 
the  wall  rock,  at  times  w 
changing  suddenly  ; 
but  where  the  vein  is 
formed  wholly  by  the 
filling  of  an  open  fis- 
sure, the  rock  exerts 
no  influence  on  the  FIG.  40.— Tabulation  of 
character  of  the  ore 
(47).  If  the  vein  is 
inclined,  the  lower  wall  is  spoken  of  as  the  foot  wall  and  the 
upper  one  as  the  hanging  wall. 

Parallel  fissures  are  not  uncommon,  but  the  several  veins 
do  not  necessarily  show  an  equal  degree  of  richness.  Where 
the  vein  is  of  composite  character,  —  that  is,  consisting  of 
closely  spaced  parallel  fissures  accompanied  sometimes  by  a 
mineralization  of  the  intervening  rock,  —  it  is  termed  a  lode. 
The  top  of  the  vein  is  called  the  apex,  and  is  occasionally 
traceable  for  a  long  distance. 

Linked  veins  represent  a  type  in  which  the  parallel  fissures 
are  connected  by  diagonal  ones  (Fig.  41),  giving  a  series 
resembling  the  links  of  a  chain. 


trikes  of  principal 
veins  in  Monte  Cristo,  Wash.,  district.  After 
Spurr,  U.  S.  Geol.  Surv.,  22d  Ann.  Kept., 
II :  810,  1902. 


240 


ECONOMIC   GEOLOGY   OF   THE   UNITED   STATES 


FIG.  41.  —Linked  veins.    After  Ordonez. 


Crash  veins  are  a  special  type  of  fissure  vein,  formed  by 
the   enlargement   of   joint  planes   and   sometimes  bedding 

planes.  They 
are  characteris- 
tic of  the  up- 
per Mississippi 
Valley  lead  and 
zinc  region,  but 
are  usually  of 
limited  extent 
and  local  impor- 
tance. In  the 
simplest  form 

they  are  a  vertical  fissure,  but  develop  into  types  shown 
in  Fig.  42. 

Filling  of  Fissure  Veins  (16).  —  The  manner  in  which 
fissure  veins  have  been  filled,  and  the  source  of  the  metals 
which  they  contain,  formed  a  most  fruitful  subject  of  dis- 
cussion among  the  earlier  geologists.  Four  general  theories 
were  advanced  at  an  early  date  (2).  They  are:  (1)  Con- 
temporaneous formation,  a 
theory  no  longer  advocated 
by  any  one.  (2)  Descension, 
which  likewise  no  longer  has 
many  adherents.  (3)  Lateral 
secretion,  in  which  the  vein 
contents  are  supposed  to  have 
been  leached  from  the  wall 
rock,  usually  in  the  immediate  vicinity  of  the  fissure,  but 
at  variable  depths  below  the  surface  ;  some  geologists  hold- 
ing this  view  believe  that  the  area  leached  was  very  exten- 


Fio.  42.  — Gash  vein  with  associated 
"flats"  (a)  and  "pitches"  (6). 
Wisconsin  zinc  region.  After  Grant, 
Wis.  Geol.  and  Nat.  Hist.  Surv., 
Bull.  IX :  62. 


ORE  DEPOSITS  241 

sive  and  not  confined  to  the  immediate  vicinity  of  the 
walls.  (4)  Ascension,  the  material  being  deposited  by  infil- 
tration, sublimation  with  steam,  sublimation  as  gas,  or 
igneous  injection.  The  several  arguments  for  or  against 
these  theories  are  well  set  forth  in  Kemp's  paper  (ref.  16), 
and  it  will  suffice  here  to  state  that  of  the  various  ones 
those  of  lateral  secretion  and  ascension  by  infiltration  are 
the  most  rational.  It  is  probable  that  the  majority  of  geol- 
ogists now  believe  in  a  modified  theory  of  lateral  secretion, 
in  which  the  area  of  supply  extends  beyond  the  immediate 
walls  of  the  fissure,  and  that  the  ore-bearing  solutions  have 
either  ascended  the  fissure  or  entered  through  the  walls. 


'B 

FIG.   43. — Section  at  Bonne  Terre,   Mo.,   showing  ore   disseminated   through 
limestone. 


limestone. 

Other  Forms  of  Ore  Deposits.  —  Impregnations  represent 
deposits  in  which  the  ore  has  been  deposited  in  the  pores  of 
the  rock,  or  the  crevices  of  a  breccia  (Keweenaw  Point, 
Michigan).  Fahlband  is  a  belt  of  schist  impregnated  with 
sulphides.  Ore  channels  include  those  ore  bodies  formed 
along  some  path  which  the  mineral  solutions  could  easily 
follow,  as  the  boundary  between  two  different  kinds  of  rock 
(Leadville,  Colorado,  Mercur,  Utah).  Bedded  deposits,  found 
parallel  with  the ;  stratification  of  sedimentary  rocks,  and 
sometimes  of  contemporaneous  origin  (Clinton  iron  ore). 
Contact  deposits,  as  now  understood,  represent  ore  bodies 
formed  along  the  contact  of  a  mass  of  igneous  and  sedimen- 
tary rock  (usually  calcareous),  the  ore  having  been  derived 


242          ECONOMIC   GEOLOGY   OF  THE  UNITED   STATES 

wholly  or  in  part  from  the  intrusive  mass  (Clifton,  Arizona, 
in  part).  Chamber  deposits,  whose  ore  has  been  deposited  in 
caves  of  solution  (Missouri  lead  and  zinc  ores).  Dissemina- 
tions, deposits  in  which  the  ore  is  disseminated  through  the 
rock  (Southeastern  Missouri  lead  ores). 

Secondary  Changes  in  Ore  Deposits.  —  Ore  deposits  may  be 
changed  in  their  upper  parts  by  weathering  agents,  while  the 
lower-lying  portions,  below  the  ground  water  level,  are  often 
enriched  by  secondary  processes. 

Weathering  or  Superficial  Alteration  (25) .  —  This  involves 
both  chemical  and  physical  changes  similar  to  the  decay  and 
disintegration  of  common  rocks,  but  the  great  number  of 
mineral  compounds  involved,  including  many  with  metallic 
base,  give  rise  to  a  large  number  of  intricate  chemical  reac- 
tions. Since  many  of  the  minerals  in  ore  deposits  are  more 
easily  decomposed  than  the  common  rock-forming  minerals, 
the  alteration  is  quite  rapid  and  extends  to  a  greater  depth 
than  in  the  country  rock.  There  is,  however,  marked  varia- 
tion in  the  rate  at  which  the  different  ore-forming  minerals 
decay,  and  this  variation  exists  even  in  a  single  group,  like 
the  sulphides  in  which  the  order  or  rate  of  decomposition  is 
arsenopyrite,  pyrite,  chalcopyrite,  blende,  galena,  chalcocite, 
and  tetrahedrite  (41). 

The  altered  portion  of  the  ore  deposit  is  known  as  the 
gossan,  or  iron  hat  (French,  chapeau-de-fer ;  German,  eisener 
Hut},  because  the  deposit  is  usually  stained  by  iron  minerals, 
such  as  limonite,  which  may  sometimes  completely  mask  the 
true  nature  of  the  ore. 

The  first  chemical  changes  are  oxidation  or  hydration,  or 
both,  and  these,  together  with  other  changes,  produce  many 


ORE   DEPOSITS 


243 


soluble  compounds,  which  can  be,  and  often  are,  leached  out 
of  the  gossan  by  percolating  waters.  An  example  of  oxida- 
tion is  the  alteration  of  pyrite  to  ferrous  and  ferric  sulphate, 
and  by  hydration  and  further  oxidation  to  limonite.  Chal- 
copyrite  oxidizes  to  copper  sulphate,  and  by  hydration  and 
further  oxidation  to  copper  carbonate,  silicate,  or  oxide.  We 
see  therefore  that  the  first  change  in  each  of  the  above  cases 
is  the  same,  sulphates  being  formed  from  sulphides,  but  the 
later  changes  are  different,  the  iron  sulphate  changing  to 
hydrous  oxide,  while  the  copper  forms  a  different  set  of  com- 


No.3  L...I  Cur  .nd  Ilolbrook 

No.  4  L...I  Car  .ad  Hoi  brook 

No.9  L...1  Holbnok 


FIG.  44. —  Section  through  Copper  Queen  Mine,  Bisbee,  Ariz.,  showing  variable 
depth  of  weathering.  After  Douglas,  Amer.  Inst.  Min.  Engrs.,  Trans. 
XXIX.,  1900. 

pounds.  Reduction  may,  however,  occur,  as  when,  for  ex- 
ample, two  partly  oxidized  salts  of  iron  and  copper  react 
with  each  other,  giving  ferric  salts  and  metallic  copper,  owing 
to  the  stronger  affinity  of  iron  for  oxygen. 

The  porosity  of  the  gossan  is  sometimes  due  to  leaching, 
sometimes  to  shrinkage,  as  when  siderite  or  pyrite  change  to 
limonite.  Hydration,  on  the  contrary,  causes  expansion. 

The  depth  of  weathering  depends  on  topographic  condi- 
tions, chemical  nature  and  porosity  of  the  deposits,  and 
climate ;  but  in  any  event  it  is  liable  to  vary  in  the  same 
deposit,  owing  to  variation  in  the  permeability  of  different 
parts  of  the  mass  (Fig.  44).  In  Arizona  many  copper  de- 


244          ECONOMIC   GEOLOGY   OF  THE   UNITED   STATES 

posits  have  been  changed  from  sulphides  to  carbonates,  to  a 
depth  ranging  from  100  to  700  feet;  the  oxidized  ores  of 
the  Appalachian  region  average  about  100  feet  in  depth ; 
while  those  of  the  Rocky  Mountain  area  range  from  50  to 
700  in  depth. 

The  ferric  sulphate  produced  by  the  weathering  of  pyrite 
is  a  most  important  factor  in  the  alteration  of  ore  deposits. 
When  formed  it  attacks  pyrite  and  other  sulphides,  convert- 
ing them  into  sulphates,  at  the  same  time  being  itself  reduced 
to  ferrous  sulphate,  which  is  in  part  changed  to  limonite  and 
sulphuric  acid.  That  portion  remaining  unreduced  begins 
anew  the  scale  of  change.  Ferric  sulphate  is  thus  the  main 
agent  by  which  the  sulphides  are  dissolved.  Moreover  it 
also  acts  as  a  solvent  of  free  gold. 

All  the  metallic  contents  are  not,  however,  leached  from 
the  gossan,  for  some  minerals  are  either  difficult  to  dissolve 
or  remain  unattacked.  Thus  in  some  cases  the  leaching 
produces  an  enrichment  by  the  removal  of  worthless  con- 
stituents and  a  consequent  increase  per  ton  of  valuable 
minerals.  The  soluble  compounds  produced  by  weathering 
are  often  carried  downward  by  percolating  water  and  de- 
posited in  an  irregular  zone  between  the  gossan  and  the 
unweathered  ore  below.  In  many  copper  deposits  there  is 
found  a  rich  zone  of  black  copper  between  the  gossan  and 
unaltered  sulphides. 

Secondary  Deposition  below  Ground  Water  Level  (4,  41).  — 
If  the  body  of  unaltered  sulphides  below  is  broken  by 
fissures,  the  solutions  containing  the  various  metallic  sul- 
phates and  sulphuric  acid  will  enter  them,  penetrating  at 
times  to  considerable  depths. 

If  pyrite  or  pyrrhotite  are  present  at  these  depths,  a  reac- 


OKE   DEPOSITS  245 

tion  occurs  between  the  ferric  sulphate,  the  dissolved  metallic 
sulphides,  and  the  pyrite.  This  may  result  in  the  precipita- 
tion of  new  sulphides  on  the  walls  of  the  fracture,  forming 
rich  patches  of  ore  or  bonanzas  (28) .  The  association  of  these 
fractures  formed  after  the  primary  sulphides  is  an  important 
character  of  value  to  the  mining  engineer,  and  from  what  has 
been  said  above,  it  can  be  seen  what  an  important  role  py- 
rite plays  in  the  secondary  enrichment  process.  It  has  been 
noticed,  however,  that  pyrite  is  not  the  only  reducing  and  pre- 
cipitating agent  in  ore  deposits.  Carbon  is  a  strong  reducer, 
and  other  minerals  also  exert  a  variable  influence  (14).  (See 
deposition  of  lead  and  zinc  in  Wisconsin  and  Ozark  region, 
Chap.  XVII.) 

Value  of  Ores.  —  The  terms  rich  and  poor,  as  applied  to 
ores,  are  used  with  great  frequency,  although  most  indefinite 
and  often  meaningless.  Under  very  favorable  conditions  it 
is  possible  to  profitably  work  an  ore  of  given  value  at  one 
locality,  while  if  found  under  other  less  favorable  conditions 
at  another  point  it  might  be  almost  worthless. 

Those  who  have  not  given  special  study  to  ore  deposits 
often  fail  to  realize  that  in  the  majority  of  ores  the  per- 
centage of  metal  contained  in  the  ore  falls  considerably 
below  the  theoretic  percentage  of  the  metallic  contents  in 
the  ore-bearing  minerals,  due  of  course  to  the  presence  of 
a  greater  or  less  quantity  of  gangue  minerals  which  tend  to 
dilute  the  metallic  values  of  the  vein.  Lake  Superior  copper 
ores  contain  as  little  as  .65  per  cent  native  copper ;  and  many 
sulphide  ores  running  as  low  as  5  or  6  per  cent  metallic 
copper  or  even  less  are  successfully  worked.  Many  low- 
grade  lead  ores  are  profitably  mined  because  their  gold  and 


246          ECONOMIC   GEOLOGY   OF   THE   UNITED   STATES 

silver  contents  more  than  pay  the  cost  of  metallurgical  treat- 
ment. Gold  ores  alone,  running  as  low  as  $2  or  $3  per  ton, 
can  likewise  be  successfully  worked  at  times.  In  many  cases 
the  metallic  contents  of  the  ore  is  increased  by  mechanical 
concentration  or  by  roasting  (in  the  case  of  sulphides),  or 
both,  before  the  ore  is  smelted. 

Classification  of  Ore  Deposits.  —  Many  attempts  have  been 
made  to  develop  a  suitable  classification  of  ore  deposits,  and 
many  schemes  have  been  suggested  (17).  These  are  usually 
based  either  on  form,  mineral  contents,  or  mode  of  origin. 
The  first  is  perhaps  the  most  practical  from  the  miner's 
standpoint,  the  second  is  undesirable  because  several  kinds 
of  ore  may  often  be  found  in  the  same  ore  body,  while  the 
third  is  the  most  scientific,  and  is  of  value  to  the  mining 
geologist  and  engineer. 

Those  desiring  to  look  into  this  phase  of  the  subject  in 
more  detail  are  referred  to  the  bibliography  at  the  end  of  this 
chapter,  especially  the  papers  by  Kemp  (17),  Posepny  (24), 
and  Van  Hise  (40). 

Only  one  classification  is  given  here,  viz.  that  of  W. 
H.  Weed,  not  because  it  is  considered  entirely  satisfactory 
or  especially  simple,  but  because  it  embodies  the  results  of 
the  more  modern  studies  of  ore  deposits  and  their  genetic 
character. 

CLASSIFICATION  OF  ORE  DEPOSITS  (AFTER  WEED) 

A.   Igneous,  magmatic  segregation. 
(a)  Siliceous. 

1.  Masses,  Aplitic  masses.     Ehrenberg,  Shartash. 

2.  Dikes,  Beresite  or  Aplite.    Berezovsk. 

3.  Quartz  veins.     Alaska,  Randsburg,  Black  Hills. 


OKE   DEPOSITS  247 

(6)  Basic. 

1.  Peripheral  masses.     Copper,  iron,  nickel. 

2.  Dikes,  titaniferous  iron.     Adirondacks,  Wyoming. 

B.  Igneous   emanations.     Deposits   formed   by   gases   above   or   near 

the  critical  point,  e.g.  365°  C.  and  200  atmospheres  for 
H2O. 
(a)  Contact  metamorphic  deposits. 

1.  Deposits  confined  to  contact.    Magnetite  deposits,  chalcopy- 

rite  deposits,  Kristiania  type,  gold  ores,  Bannock  type. 

2.  Deposits  impregnating  and  replacing  beds  of  contact  zone. 

Chalcopyrite  deposits,  pyrrhotite  ores,  magnetite  ores,  Can- 
anea  type,  Gold  tellurium  ores,  Elkhorn  type,  Arsenopyrite 
ores,  Similkameen  type. 
(6)  Veins  closely  allied  to  magmatic  veins  and  to  Division  D. 

1.  Cassiterite.     Cornwall. 

2.  Tourmaline  copper.     Sonora. 

3.  Tourmaline  gold.     Helena,  Mont.,  Minas  Geraes,  etc. 

4.  Augite  copper,  etc.     Tuscany. 

C.  Fumarolic  deposits. 

(a)  Metallic  oxides,  etc.,  in  clefts  in  lava.     No  commercial  impor- 
tance.    Copper,  iron,  etc. 

D.  Gas-aqueous  or  pneumato-hydato-genetic  deposits,  igneous  emana- 

tions, or  primitive  water  mingled  with  ground  water, 
(a)  Filling  deposits. 

1.  Fissure  veins. 

2.  Impregnation  of  porous  rock. 

3.  Cementation  deposits  of  breccia. 
(6)  Replacement  deposits. 

1.  Propylitic.     Comstock. 

2.  Sericitic  kaolinic,  calcitic,  Copper  silver,  Silver  lead.   Clausthal. 

3.  Silicic  dolomitic,  silver  lead,  aspen. 

4.  Silicic  calcitic,  cinnabar. 

5.  Sideritic  silver  lead.     Coeur  d'Alene,  Slocan,  Wood  River. 

6.  Biotitic  gold  copper.     Rossland. 

7.  Fluoric  gold  tellurium.     Cripple  Creek. 

8.  Zeolitic. 


248          ECONOMIC   GEOLOGY   OF   THE   UNITED   STATES 

Structure  Types  of  Above 
Fissure  Veins. 

Volcanic  stocks,  Nagyag.     Cripple  Creek. 
Contact  chimneys.    Judith. 
Dike  replacements  and  impregnations. 
Bedding  or  contact  planes.    Leadville,  Mercur. 
Axes  of  folds,  synclinal  basins,  anticlinal  saddles.    Bendigo, 
Elkhorn. 

E.  Meteoric  waters.     Surface  derived, 
(a)  Underground. 

1.  Veins. 

2.  Replacements.    Iron  ores,  Michigan ;  copper  ores,  Michigan ; 

lead,  zinc. 

3.  Residual.     Gossan  iron  ores,  manganese  deposits. 
(6)  Surficial. 

1.  Chemical.     Bog  iron  ores,  copper  ores,  sinters. 

2.  Mechanical.     Gold  and  tin  placers. 
Sedimentary  beds,  iron  ores,  etc. 

F.  Metamorphic   deposits.      Ores   concentrated   from    older   rocks   by 

metamorphism,  dynamo  or  regional. 

Igneous  ore  deposits,  forming  the  first  division,  are  those 
in  which  the  metallic  minerals  have  crystallized  directly 
from  the  igneous  magma  during  cooling. 

The  pneuinatolytic  deposits  include  those  formed  along 
igneous  contacts,  the  material  being  supplied  by  the  in- 
trusive, as  explained  on  an  earlier  page. 

The  gas-aqueous  deposits  include  those  which  have  been 
deposited  from  a  mixture  of  water  and  steam,  probably  under 
pressure  and  at  high  temperature.  They  may  either  fill  true 
fissures  or  porous  deposits,  or  replace  the  wall  rock  lining 
a  narrow  fissure.  It  will  be  seen  that  the  types  mentioned 
under  B  and  C  might  pass  into  each  other.  The  same 
igneous  mass  could  at  great  depths  give  off  metallic  min- 


ORE   DEPOSITS  249 

erals  under  conditions  mentioned  under  B,  while  higher 
up  the  emission  from  it  would  yield  a  deposit,  classifiable 
under  C. 

Fumarolic  deposits  include  those  in  which  metallic  com- 
pounds are  deposited  from  volcanic  vapors  or  gases  in  clefts 
in  lavas.  They  are  of  no  commercial  importance. 

The  last  class  is  the  result  of  meteoric  circulation,  the 
waters  having  collected  the  ore  particles  from  the  rocks 
through  which  they  moved,  and  deposited  them  under  favor- 
able conditions,  either  on  the  surface  or  below  it. 

REFERENCES  ON  ORE  DEPOSITS 

GENERAL.  1.  Barus,  Amer.  Inst.  Min.  Engrs.,  Trans.  XIII :  417,  1885. 
(Electrical  activity  in  ore  bodies.)  2.  von  Cotta-Prime,  Ore  De- 
posits (English  translation  by  Prime,  N.  Y.,  1870).  3.  Don,  Amer. 
Inst.  Min.  Engrs.,  Trans.  XXVII :  564,  1898.  (Genesis  of  gold.) 
4.  Emmons,  Amer.  Inst.  Min.  Engrs.,  Trans.  XXX  :  177,  1901.  (Sec- 
ondary enrichment  ore  deposits.)  5.  Emmons,  Amer.  Inst.  Min. 
Engrs.,  Trans.  XXII :  53,  1894.  (Geol.  distribution  useful  metals.) 
6.  Emmous,  Geol.  Soc.  Amer.,  Bull.  XV  :  1,  1904.  (Theories  of  ore 
deposition.)  7.  Emmons,  Amer.  Inst.  Min.  Engrs.,  Trans.  XVI:  804, 
1888.  (Structural  relations  of  ore  deposits.)  8.  Emmons,  Colo.  Sci. 
Soc..  Proc.  II  :  189.  1885-7.  (Origin  of  fissure  veins.)  9.  Fox, 
Amer.  Jour.  Sci.  i,  XXXVII :  199?  1839.  (Vein  formation  by  gal- 
vanic agency.)  10.  Fuchs  et  De  Launay,  Traite  des  Gites  Mineraux 
et  Metallif eres,  Paris,  1893.  11.  Finch,  Colo.  Sci.  Soc.,  Proc.  VII :  193, 
1904.  (Underground  waters  and  ore  deposition.)  12.  Glenn,  Amer. 
Inst.  Min.  Engrs.,  Trans.  XXV :  499, 1896.  (Fissure  walls.)  13.  Gil- 
lette, Amer.  Inst.  Min.  Engrs.,  Trans.  XXXIV:  710.  (Osmosis 
theory.)  14.  Jenney,  Amer.  lust.  Min.  Engrs.,  Trans.  XXXIII:  445, 
1904.  (Chemistry  of  ore  deposition.)  15.  Kemp,  S.  of  M.  Quart., 
X:  54,116,  326,  1889;  XI:  359,1890;  XII :  218,  1891.  (Literature 
on  ore  deposits.)  16.  Kemp,  S.  of  M.  Quart.,  XIII :  20,  1892.  (Fill- 
ing of  veins.)  17.  Kemp,  S.  of  M.  Quart.,  XIV  :  8, 1893.  (Classifi- 
cation of  ore  deposits.)  18.  Kemp,  Min.  Indus.,  IV:  755,  1896. 
(Theories  of  origin  of  ores.)  19.  Kemp,  Ore  Deposits  of  United 
States  and  Canada,  N.  Y.,  1903.  20.  Kemp,  Amer.  Inst.  Min.  Engrs., 
Trans.  XXXIII  :  699,  1903.  (Relation  of  igneous  rocks  to  ore 
deposition.)  21.  Kemp,  Amer.  Inst.  Min.  Engrs.,  Trans.  XXXI :  169, 


250          ECONOMIC   GEOLOGY  OF   THE   UNITED   STATES 

1901.  (Igneous  rock  and  vein  formation.)     22.  Lindgren,  Amer. 
Inst.  Min.  Engrs.,  Trans.  XXX  :  578, 1901.     (Metasomatic  processes 
in  fissure  veins.)     23.  Lindgren,  Amer.  Jour.  Sci.  iv,  V :  418,  1898. 
(Orthoclase  gangue.)     24.  Posepny,  Amer.  Inst.  Min.  Engrs.,  Trans. 
XXIII:  197,  1894.     (Genesis  of  ore  deposits.)      25.  Penrose,  Jour. 
Geol.,  II :  288,  1894.     (Weathering  of  ore  deposits.)     26.   Phillips, 
Treatise  on  Ore  Deposits,  London,  1884.     27.  Rickard,  Eng.  and 
Min.  Jour.,  LXXIII :  106,  1902.     (Recent  advances  in  study  of  ore 
deposits.)     28.  Rickard,  Amer.  Inst.  Min.  Engrs.,  Trans.  XXXI :  198, 

1902.  (Bonanzas  in  gold  veins.)     29.   Rickard,  Amer.  Inst.  Min. 
Engrs.,  Trans.  XXVI :  193,  1897.    (Vein  walls.)     30.  Rickard,  Eng. 
and  Min.  Jour.,  LXV  :  494,  1898.     (Minerals  accompanying  gold.) 

31.  Sandberger,  Untersuchungen  iiber  Erzgange,  Wiesbaden,  1882. 

32.  Suess,  Eug.  and  Min.  Jour.,  LXXVI :  52,  1903.     (Hot  springs.) 

33.  Spurr,  Eng.  and  Min.  Jour.,  LXXVI :  54,  1903.     (Relation  of 
rock  segregation  to  ore  deposition.)     34.  Spurr,  Amer.  Inst.  Min. 
Engrs..  Trans.  XXXIII :  288,  1903.    (Magmatic  segregation  of  rocks 
and  ores.)     35.  Vogt,  Zeitsch.  f.  Prak.  Geol.,  1 :  4,  125,  257,  1893. 
(Magmatic  segregation  of  ores.)     36.   Vogt,  Min.  Indus.,  IV :  743, 
1896.     (Formation  of  eruptive  ore  deposits.)      37.   Vogt,  Zeitsch. 
f.  Prak.  Geol.,  VI :  225,  314,  377,  413,  1898 ;  VII :  10,  1899.      (Dis- 
tribution of  elements  and  concentration  of  metals  in  ore  bodies). 
38.  Vogt,  Amer.  Inst.  Min.  Engrs.,  Trans.  XXXI :  125, 1902.   (Prob- 
lems in  geology  of  ore  deposits.)     39.  Van  Hise,  Amer.  Inst.  Min. 
Engrs.,  Trans.  XXX:  27,1901.   (Deposition  of  ores.)    40.  Van  Hise, 
U.  S.  Geol.  Surv.,  Mon.  XLVII,  1905.  (Metamorphism.)     41.  Weed, 
Amer.  Inst.  Min.  Engrs.,  Trans.  XXX :  424,  1901.  (Enrichment,  gold 
and  silver  veins.)    42.  Wagoner,  Amer.  Inst.  Min.  Engrs.,  Trans. 
XXXI :  798, 1902.  (Gold  and  silver  in  sedimentary  rocks.)  43.  Weed, 
Eng.  and  Min.  Jour.,  LXXVI:  193,  1903.     (Cross  vein  ore  shoots.) 
44.   Weed,  Eng.  and  Min.  Jour.,  LXXIV:  545,  1903.      (Vein  en- 
richment by  ascending  alkaline  waters.)     45.   Weed,  Eng.  and  Min. 
Jour.,  LXXIV:    513,   1902.     (Contact  deposits.)     Also  Lindgren. 
46.   Weed,  Amer.  Inst.   Min.  Engrs.,  Trans.  XXXIII:    747,  1903. 
(Vein   enrichment  by  ascending   hot  waters.)      47.   Weed,  Amer. 
Inst.  Min.  Engrs.,  Trans.  XXXI :  634,  1902.     (Influence  of  wall  rock 
on  mineral  veins.)     48.   Weed,  U.  S.  Geol.  Surv.,  Bull.  260,  1905. 
(Hot  spring  deposits.)      49.   Weed,  U.   S.   Geol.  Surv.,  21st  Ann. 
Rept.,  II :  227, 1900.     (Hot  springs  depositing  gold.)     50.  Whitney, 
Metallic  wealth  of  U.  S.,  Phil.,  1854.     51.   Weed,  Amer.  Inst.  Min. 
Engrs.,  Trans.  XXXIH :  731, 1903.    (Contact  deposits.) 


CHAPTER  XIV 
IRON  ORES 

IRON  is  an  abundant  constituent  of  the  earth's  crust,  and 
yet  few  minerals  are  capable  of  serving  as  ores  of  this  metal, 
because  they  do  not  contain  it  in  the  right  combination  or 
in  sufficient  quantity  to  make  its  extraction  possible  or 
profitable. 

The  iron  ores  having  the  greatest  commercial  value  at  the 
present  day  are  usually  those  which  are  favorably  located, 
of  high  quality,  in  considerable  quantity,  and  possessing  a 
structure  such  as  to  render  their  extraction  easy.  These 
four  requirements  have  been  met  to  such  an  eminent  degree 
by  the  deposits  located  in  the  Lake  Superior  district  that 
they  now  form  the  main  source  of  supply  for  furnaces  in 
the  Eastern  and  Central  states,  many  of  the  iron  mines  in 
the  eastern  part  of  the  United  States  having  been  forced  to 
shut  down,  although  it  is  true  that  a  number  of  small 
deposits  are  worked  to  supply  local  demand,  owing  to  their 
proximity  to  furnace,  flux,  and  coal,  or  because  they  possess 
certain  desirable  characteristics. 

Ores  of  Iron. — The  ores  of  iron,  together  with  their  com- 
position and  theoretic  percentage  of  metallic  iron,  are  :  — 

MAGNETITE.     Magnetic  iron  ore.     Fe3O4     .     .     .     .     .     72.4    per  cent. 
HEMATITE.       Specular  iron  ore,  red  hematite,  fossil  ore, 

clinton  ore.     Fe2O3 70       per  cent. 

251 


252          ECONOMIC   GEOLOGY   OF   THE  UNITED   STATES 

LIMONITE.        Brown  hematite,   bog    iron    ore,   ocher. 

2  Fe2O3,  3  H2O 59.89  per  cent. 

SIDERITE.  Spathic  ore,  blackband,  clay  ironstone, 

kidney  ore.  FeCO8 48.27  per  cent. 

PYKITE.  FeS2 46.7  percent. 


Of  these  hematite  is  the  most  valuable  by  far,  chiefly  on 
account  of  its  easier  reduction,-  but  also  because  of  the 
greater  richness  of  the  known  important  deposits.  The 
deficiency  in  iron  contents  shown  by  many  ores  is  due  to 
the  presence  of  common  rock-forming  minerals  in  the 
gangue,  the  impurities  yielded  by  them  being :  alumina, 
lime,  magnesia,  silica,  titanium,  arsenic,  copper,  phosphorus, 
and  sulphur. 

The  effect  of  the  last  six  is  to  weaken  the  iron  in  general. 
While  silica  in  high  amounts  is  not  desirable,  still  some  fur- 
naces turn  out  iron  for  foundry  purposes  containing  10  or 
more  per  cent.  Pyrite  is  the  source  of  the  sulphur,  and 
apatite  of  the  phosphorus.  Titanium,  a  common  but  injuri- 
ous ingredient,  is  found  in  many  magnetite  deposits  (see 
Titaniferous  magnetites  ;  also  refs.  20,  21),  and  up  to  the 
present  time  has  rendered  them  practically  useless,  not 
because  it  interferes  with  the  quality  of  the  iron,  but 
because  it  makes  the  ore  highly  refractory,  and  drives 
much  of  the  iron  into  the  slag.  Experiments  have  been 
undertaken  looking  towards  the  utilization  of  these  titan- 
iferous  magnetites  for  the  manufacture  of  ferro-titanium. 
Manganese,  when  present,  is  found  mostly  in  the  limonite 
ores,  and  for  certain  purposes  is  desirable.  It  is  also  promi- 
nent in  some  of  the  Lake  Superior  hematites. 

As  phosphorus  cannot  be  eliminated  in  either  the  blast  furnace  or  the 
acid  converter  used  in  making  Bessemer  steel,  and  as  the  allowable  limit 


IRON   ORES 


253 


of  phosphorus  in  pig  iron  used  for  this  purpose  is  TJa  percent,  a  distinction 
is  usually  made  between  Bessemer  and  non-Bessemer  ores,  the  maximum 
amount  of  phosphorus  permissible  in  iron  ore  to  be  used  for  this  purpose 
being  ^^  of  the  percentage  of  metallic  iron  contents  of  the  ore.  The 
phosphorus  content  of  many  high-grade  ores,  however,  falls  considerably 
below  the  allowable  limit. 

With   the   exception   of  iron   ores   formed  by  magmatic 
segregation,  gas-aqueous  action,  and  some  deposits  of  sedi- 


FIG.  45.  —  Map  showing  distribution  of  iron  ores  in  the  United  States.    Adapted 
from  Ransome,  Min.  Mag.,  X :  1. 

mentary  character,  most  iron  ores  owe  their  concentra- 
tion to  the  action  of  circulating  meteoric  waters,  which 
have  leached  the  iron  out  of  the  rocks  and  deposited  it 
under  favorable  conditions  either  in  cavities  or  by  replace- 
ment. 

The  ore  most  commonly  formed  in  this  manner  is  limonite, 
and  the  deposits  are  of  surficial  character,  but  hematite  bodies 
of  similar  origin  are  known.  Deposits  of  siderite  formed 


254          ECONOMIC   GEOLOGY   OF  THE  UNITED   STATES 

by  replacement  are  frequently  changed  to  limonite  by 
weathering.  Iron-ore  bodies  may  show  a  variety  of  form, 
but  most  of  those  known  in  this  country  are  lens-shaped 
or  basin-shaped  in  outline. 

The  iron  ores  found  in  the  United  States  are  widely  dis- 
tributed (Fig.  45),  and  their  age  ranges  from  pre-Cambrian 
to  recent.  The  occurrence  and  distribution  of  the  different 
kinds  of  ore  are  best  discussed  separately. 

MAGNETITE 

Magnetite  occurs  in  the  United  States,  (1)  as  lenticular 
masses  commonly  in  metamorphic  rocks;  (2)  as  more  or 
less  lens-shaped  bodies  in  igneous  rocks;  (3)  as  sands  on  the 
shores  of  lakes  and  seas;  and  (4)  as  contact  deposits. 

The  first  class  includes  the  most  important  deposits  now 
worked  in  this  country.  The  second  and  third  groups  run 
too  high  in  titanium  to  have  any  commercial  value  at  the 
present  time,  but  the  second  may  become  of  importance  in 
the  future,  and  moreover  some  of  the  deposits  of  this  group 
are  of  large  size.  Undoubted  representatives  of  the  fourth 
class  of  commercial  value  are  not  worked.  There  are  some, 
it  is  true,  which  occur  along  the  contact  of  an  intrusive  and 
sedimentary  rock,  but  their  origin  is  ascribed  to  meteoric 
circulations. 

Distribution  of  Magnetites  in  the  United  States.  —Non- 
Titaniferous  Magnetites.  — These  are  usually  found  in  the 
form  of  lenticular  deposits  in  metamorphic  rocks.  The 
most  important  series  of  occurrences  is  found  in  the  crys- 
talline belt  of  rocks  extending  from  New  York  into  Alabama, 
deposits  being  known  in  New  York,  New  Jersey,  Pennsyl- 
vania, Virginia,  and  North  Carolina. 


PLATE  XIV 


FIG.  1.— View  of  open  cut  in  magnetite  deposit,  Mineville,  N.Y.  The  pillars  are 
ore  left  to  support  the  gneiss  hanging  wall.  After  Witherbee,  Iron  Age,  Dec.  17, 
1903. 


FIG.  2. —  General  view  of  magnetic  separating  plants  and  shaft  houses,  Mineville, 
N.Y.    After  Witherbee,  Iron  Age,  Dec.  17, 1903. 


IRON  OKES  255 

The  lenses,  which  are  interbedded  with  the  gneisses  of 
either  acid  or  basic  character  and  often  conform  with  the 
latter  in  dip  and  strike,  are  of  variable  size,  and  may 
occur  either  singly  or  in  series,  the  ore  body  commonly 
showing  pinching  and  swelling,  or  even  faulting.  Well- 
defined  boundaries  are  sometimes  wanting.  Feldspar, 
hornblende,  and  quartz  are  common  gangue  minerals, 
while  apatite  is  prominent  in  some.  Although  the  ore 
as  mined  is  frequently  of  sufficient  purity  to  be  shipped 
direct  to  the  blast  furnace,  in  some  instances  it  is  so  lean  as 
to  require  concentration  by  magnetic  methods.  This  same 
plan  has  been  adopted  at  Mineville,  New  York,  to  treat  the 
high  phosphorus  magnetite,  thereby  yielding  a  rich  con- 
centrate (68  per  cent  Fe)  for  iron  manufacture,  a  fairly 
pure  apatite  used  in  making  fertilizers,  and  a  hornblende 
tailings  or  waste  product. 

The  magnetites  have  been  extensively  worked  on  the 
northern  and  eastern  side  of  the  Adirondacks,  notably  at 
Mineville  (19),  where  one  lens  has  been  traced  for  a  distance 
of  2000  feet.  Many  ore  bodies  have  also  been  mined  in 
New  Jersey,  where  they  are  disposed  in  more  or  less 
parallel  belts. 

The  origin  of  these  magnetites  has  been  a  subject  of 
much  discussion,  but  their  interfoliation  with  the  gneisses 
is  thought  by  some  to  indicate  that  the  ores  and  rock  had  a 
common  origin.  Those  believing  the  gneisses  to  be  meta- 
morphosed sediments  thought  the  magnetites  were  originally 
limonite,  but  if  the  gneisses  are  metamorphosed  igneous 
rocks,  then  the  ore  may  represent  magmatic  segregations. 
The  North  Carolina  magnetites  have  been  suggested  by 
Keith  (18  a)  to  be  replacement  deposits,  while  Kemp  be- 


256          ECONOMIC   GEOLOGY   OF   THE  UNITED   STATES 

lieves  that  the  ore  bodies  at  Mineville  (19)  have  been  formed 
by  iron-bearing  magmatic  waters,  which  were  given  off 
from  the  neighboring  gabbros  and  penetrated  the  gneisses, 
while  the  latter  were  probably  still  at  great  depths  and 
before  their  metanaorphism  was  complete.  The  presence 
of  apatite  and  fluorite  shows  that  mineralizing  vapors  also 
played  a  part.  A  similar  origin  has  recently  been  suggested 
by  Spencer  (23)  to  explain  some  of  the  New  Jersey  magnetites. 
Other  theories  advanced  are  that  the  magnetite  deposits  were 
formed  as  beach  sands  or  even  river  bars,  but  such  an  as- 
sumption would  require  the  gneisses  to  be  metamorphosed 
sediments. 

A  somewhat  unique  deposit  and  one  of  the  largest  ever 
worked  occurs  at  Cornwall  (17),  Pennsylvania,  where  a  bed 
of  soft  magnetite  with  some  pyrite  is  found  between  Cam- 
brian limestone  and  Triassic  shales,  and  against  igneous 
dikes.  Their  age  has  been  placed  .as  both  Cambro-Silurian 
and  also  Triassic,  and  whether  they  represent  metamor- 
phosed pyritiferous  shale  or  limonites  is  also  unsettled. 
The  ore  runs  from  40  to  55  per  cent  Fe  and  usually 
under  .02  P,  but  is  rather  high  in  S  and  SiO2. 

Other  Occurrences.  —  Magnetite  occurs  sparingly  in  the 
Marquette  range  of  Michigan,  where  it  is  found  in  the 
schists.  Other  western  occurrences  include  Colorado  (6), 
Utah  (32),  Wyoming  (la),  New  Mexico  (la),  and  California. 

In  the  table  given  below  there  will  be  found  the  analyses 
of  a  number  of  magnetite  samples  from  eastern  mines. 

These  it  will  be  seen  show  considerable  variation  in  their 
metallic  iron  contents,  and  are  not  all  to  be  regarded  as  a 
strict  average  of  the  region  which  they  represent. 


IRON   ORES 


257 


ANALYSES  OF  MAGNETITES 


Fe 

810, 

P 

Mn 

Al,08 

CaO 

MgO 

8 

TiO, 

Alk 

u,o 

FeS, 

Belvidere,  N.J.     . 
Little  Mine,  N.J.  . 

51.42 
67.54 

8.85 
1.20 

1.048 
.02 

.17 
.90 

3.86 
.74 

1.68 
.31 

.18 
.51 

.08 

Tr 

McKtiightstown, 
Adams  Co.,  Pa.  . 

46.90 

17.054 

P*0, 
.128 

MnO 
.896 

4.424 

1.868 

4.198 

.953 

5.00 

.05 

Dillsburg,  York  Co. 
Pa  

45.00 

20.33 

P»05 
.107 

MnO 
.036 

3.775 

5.604 

4.129 

80, 
1.105 

1.14 

1.605 

Cornwall,  Pa.   .    . 

42.70 

P 
.135 

3.411 

.62 

Mineville,  N.Y. 
(Mine  21)  .     .     . 

62.10 

P 

1.198 

Titaniferous  Magnetites.  —  These  form  a  peculiar  class  by 
themselves,  and  with  only  one  or  two  exceptions  are  found 
always  associated  with  rocks  of  the  gabbro  family.  The 
ore  bodies  occur  in  the  midst  of  igneous  intrusions,  and 
according  to  Kemp  (19,  20,  21),  seem  to  have  been  formed 
by  the  segregation  of  fairly  pure  titaniferous  iron  oxide, 
either  before  or  during  the  process  of  cooling  and  con- 
solidation. 

Mineralogically  they  may  contain  both  ilmenite,  FeO, 
TiO2  (FeO,  46.75 ;  TiO2,  53.25),  and  titaniferous  magnetite, 
which  is  of  variable  composition.  The  gangue  minerals 
may  be  pyroxene,  brown  hornblende,  hypersthene,  enstatite, 
olivine,  spinel,  garnet,  and  plagioclase.  The  ores  are  usu- 
ally low  in  phosphorus  and  sulphur,  but  Va,  Cr,  Ni,  and 
Co  are  almost  always  present.  In  the  United  States  they 
are  found  in  New  York,  New  Jersey,  Colorado,  Minnesota, 
and  several  other  states,  but  are  not  worked. 

The  following  analyses  illustrate  their  composition  :  — 


258 


ECONOMIC   GEOLOGY   OF   THE  UNITED   STATES 


AXALYSES   OF   TlTANIFEROUS   MAGNETITES 


1 

2 

3 

4 

FeO 

| 

f  27  95  ] 

Fe2O3  

70.50  J 

80.78 

|  15  85  J 

79.78 

Ti02   
SiO2    

14.00 
8.60 

12.09 
2.02 

15.66 
1790 

12.08 
.75 

Al  O 

400 

258 

1023 

462 

Cr,O3  

2.40 

.51 

.32 

V..O* 

55 

Tr 

MnO    

Tr 

.28 

CaO     

1.60 

286 

.13 

MgO 

230 

604 

204 

H2O     

04 

PoO 

03 

14 

101.00 

99.90 

99.05 

100.00 

1.  Grape  Creek,  Colo. 

2.  Mayhew  Range,  Minn. 


3.  Split  Rock,  N.Y. 

4.  Greensboro,  N.C. 


Magnetite  Sands.  —  These  are  found  in  those  regions 
where  the  beach  sands  are  composed  of  weathering 
products  of  metamorphic  and  igneous  rocks.  The  sorting 
action  of  the  waves  serves  to  carry  the  heavy  mineral 
grains  high  up  on  the  beaches,  where  they  form  black 
streaks,  composed  mostly  of  magnetite  (usually  titanifer- 
ous),  mixed  with  monazite,  apatite,  and  other  heavy  min- 
erals. 

Deposits  are  known  in  this  country  on  the  shores  of 
Lake  Champlain,  Long  Island,  etc.,  but  they  are  of  small 
extent  as  well  as  lacking  in  quality. 

New  Zealand  and  Brazil  are  said  to  possess  magnetite 
sands  of  commercial  value. 


IRON   ORES 


259 


HEMATITE 

This  is  by  far  the  most  important  ore  of  iron  in  the 
United  States,  having  in  1903  formed  86.6  per  cent  of 
the  total  production.  Its  distribution,  however,  is  rather 
restricted,  and  about  five  sixths  of  the  total  quantity  mined 
came  from  the  Lake  Superior  region.  The  varieties  mined 
in  the  United  States  include  the  earthy,  specular,  oolitic, 
and  fossiliferous.  Most  of  the  deposits  belong  to  the 
replacement  type  and  are  basin-shaped,  while  bedded  and 
contact  deposits  are  also  known,  but  the  last  are  not  worked. 


Fio.  46.  —  Map  of  Lake  Superior  iron  regions,  shipping  ports,  and  transportation 
lines.    After  Grant,  Min.  Mag.,  X:  175. 

Distribution  of  Hematite  Ores  in  the  United  States.  —  At 
the  present  day  there  are  but  two  very  important  hematite 
producing  regions,  viz.  the  Lake  Superior  region  and  the 
Birmingham,  Alabama,  area. 

Lake  Superior  Region — Under  this  head  are  included  a  great 
series  of  deposits  lying  in  the  region  surrounding  the  south 
and  west  sides  of  Lake  Superior  (13).  The  rocks  are  of  remote 
geological  age,  as  can  be  seen  from  the  following  section: — 


260 


ECONOMIC    GEOLOGY   OF   THE    UNITED   STATES 


Cambrian.  Lake  Superior  sandstone. 

J  Upper  sedimentary,  or  copper  series. 

\  Lower  igneous,  with  interstratified  sediments. 

f  Sedimentaries  with  local  volcanics,  and  cut  by  Upper 
Upper  Huronian.  \  . 

[     Huronian  and  Keweenawan  intrusions. 

Lower  Huronian.     Sediments  with  some  volcanics,  cut  by  intrusives. 
Archaean  or  f  Mainly  ancient  igneous  rocks  and  some  sediments. 

Basement  com-     I      These  igneous  intrusions  pierced  by  many  others 
plex.  [     of  later  date. 

Each  of  the  above  series  is  separated  from  its  neighbor 
by  a    great   unconformity,   due   to   intervals   of    elevation 

above  the  sea  level  and 
periods  of  erosion. 

The  rocks  of  the  iron- 
bearing  formations  are 
cherty  iron  carbonates; 
ferrous  silicate  rocks ; 
pyritic  quartz  rocks 
(Archaean);  ferrugin- 
ous slates ;  ferruginous 
cherts;  jaspilites;  am- 
phibolites  and  magne- 
tite schists ;  iron  ore 
deposits;  detrital  fer- 
ruginous rocks  from 
foregoing.  Since  their 
formation  they  have 
been  folded,  faulted, 


FIG.  47.  —  Sections  of  iron-ore  deposits  in  Mar- 


and    sometimes    brec- 

111    111*11- 

quette  range.    After  Van  Hise.  ciated,  and  it  IS  in  the 

troughs   formed   by  folding  that   the  ore  usually   occurs 
(Fig.  47). 


PLATE  XV 


FIG.  1.  —  Ircm  mine,  Soudan,  Minn.    Shows  old  open  pit  with  jasper  horse  in  middle. 


FIG.  2.  —  Outcrop  of  Clinton  iron  ore,  Red  Mountain,  near  Birmingham,  Ala. 
Photo,  from  Tennessee  Coal  and  Iron  Company. 


IRON   ORES  261 

The  Archaean,  Lower  Huronian,  and  Upper  Huronian  are 
the  most  productive  iron-bearing  formations,  the  last  men- 
tioned containing  the  ore  at  two  horizons,  viz.  near  its  base 
and  in  its  central  portion. 

Six  districts,  or  ranges,  are  recognizable  in  the  Lake 
Superior  region,  viz.  Marquette  (13)  and  Crystal  Falls  (27) 
in  Michigan ;  Menominee  (25)  in  Wisconsin ;  Penokee- 
Gogebic  (37)  on  the  Michigan- Wisconsin  boundary;  Mesabi 


FIG.  48.  —  Generalized  vertical   section   through   Penokee-Gogebic  ore  deposit 
and  adjacent  rocks ;  Colby  mine,  Bessemer,  Mich.    After  Leith. 

(31)  and  Vermilion  (28)  in  Minnesota.  The  general  mode 
of  occurrence  of  the  ore  in  several  of  these  is  shown  in 
Figs.  47,  48,  and  49. 

The  ore  is  not  found  at  the  same  horizons  in  all  the  districts,  the 
Marquette  being  the  only  one  where  all  the  iron-bearing  formations 
of  the  series  are  found.  Of  these,  the  Archaean  iron-bearing  forma- 
tions are  unproductive,  the  chief  ore  bodies  lying  within  the  Lower 
Huronian  and  at  the  base  of  the  Upper  Huronian.  In  the  Crystal 
Falls  district,  the  iron-bearing  horizon  of  the  Lower  Huronian  carries 
the  ore  as  well  as  the  horizon  within  the  Upper  Huronian.  In  both  the 


262 


ECONOMIC   GEOLOGY  OF   THE   UNITED   STATES 


Penokee  and  Mesabi  districts  the  conditions  are  similar  to  those  in 
the  western  part  of  the  Crystal  Falls  district,  the  ore  being  found  in  a 
single  formation  in  the  Upper  Huronian,  while  the  same  one  in  the 
Marquette  region  is  thin  and  of  little  consequence. 

The  smaller  deposits  are  associated  with  plications,  folding,  brecci- 
ations,  etc.,  but  the  larger  masses  of  ore  occur  at  the  contact  of  the 
iron-bearing  formations  with  others  or  between  different  members  of 
the  iron-bearing  formations.  These  contacts  were  favorable  for  con- 
centration of  ore,  because  they  are  planes  or  horizons  of  slipping,  and 
the  effect  of  this  movement  would  be  to  loosen  the  rock,  thus  making 
channels  for  the  percolating  water.  Underlying  the  deposits  of  first 


Fio.  49.  —  Generalized  vertical  section  through  Mesabi  ore  deposit  and  adjacent 
rocks.    After  Leith. 

magnitude  there  occur  impervious  formations  which  are  bent  into 
troughs.  Slate,  quartzite,  limestone,  or  igneous  rock  may  all  serve  as 
floors,  or  two  may  combine,  as  in  the  Penokee-Gogebic  district,  where 
the  trough  is  formed  by  the  intersection  of  quartzite  and  dikes.  The 
ore  bodies  are  often  U-shaped  in  section,  being  thickest  at  the  bottom. 

The  origin  of  these  ores  has  for  years  been  a  puzzling 
problem  to  geologists  (37).  Foster  and  Whitney  considered 
them  eruptive,  while  Brooks  and  Pumpelly  looked  upon  them 
as  altered  limonite  beds.  In  recent  years  the  studies  of 
Irving  and  Van  Hise  (37),  aided  by  others,  have  demon- 
strated that  the  ores  owe  their  origin  partly  to  a  replace- 
ment of  the  chert.  The  trough-shaped  location  shows  that 


IRON   OKES  263 

the  deposits  were  formed  after  the  rocks  had  been  folded, 
and  it  is  also  noticed  that  these  troughs  are  even  still  the 
lines  of  underground  waters.  That  they  have  been  produced 
by  descending  waters  is  shown  by  the  fact  that  they  are  on 
the  upper  side  of  the  impervious  bed,  and  because  the  ores 
are  oxidized  ones,  viz.,  hematite  and  limonite. 

The  chemistry  of  the  process  is  thought  to  be  as  follows :  Part  of  the 
ferric  oxide  was  deposited  as  an  original  sediment  containing  silica  and 
other  impurities,  or  in  some  cases  as  sulphides  or  carbonates.  This  was 
later  enriched  by  the  addition  of  iron  carbonate.  These  were  originally 
contained  in  the  rocks  near  the  surface,  and  became  oxidized  by  perco- 
lating waters,  which  took  up  the  carbon  dioxide  liberated,  and  were  thus 
able  to  dissolve  iron  carbonates  or  silicates,  which  they  came  in  contact 
with  in  their  downward  course  toward  the  troughs  in  which  the  ore  is 
found. 

The  precipitation  of  the  ore  was  then  caused  by  these  solutions 
meeting  with  others  which  had  filtered  in  by  a  more  open  and  direct 
path  from  the  surface,  and  hence  contained  some  free  oxygen,  which 
converted  the  dissolved  iron  compounds  into  oxides. 

The  same  solutions,  carrying  carbon  dioxide,  dissolved  the  alkalies 
out  of  the  basic  igneous  rocks  and  these  waters  were  then  able  to  dis- 
solve silica.  In  some  cases  the  solution  of  silica  proceeded  faster  than 
the  deposition  of  the  iron  ore,  and  made  the  rock  quite  porous.  The 
general  result  was  therefore  a  concentration  of  the  iron  and  removal 
of  silica. 

The  ores  of  the  Lake  Superior  region  vary  from  hard 
blue  ores  to  soft  earthy  ones.  They  are  mostly  hematite, 
with  small  quantities  of  limonite,  but  some  magnetite  is 
known  in  the  Marquette  district.  The  following  table  taken 
from  Birkenbine's  report  gives  a  number  of  typical  analyses 
(la).  Many  additional  ones  can  be  found  in  the  reports  on 
Mineral  Resources  issued  annually  by  the  United  States 
Geological  Survey. 


264 


ECONOMIC   GEOLOGY   OF   THE   UNITED   STATES 


TYPICAL  ANALYSES  OF  LAKE  SUPERIOR  IRON  ORES 


CONTENT 

MARQUETTE 
RANGE 

MENOMINEE 
RANGE 

GOGEBIC 

RANGE 

VERMILION 
RANGE 

MESABI 
RANGE 

Iron     

56.5 

55.2423 

56.308 

61.36 

56.0990 

Phosphorus  .     .     . 
Silica  ....    „. 

.0353 
4.584 

.0594 
6.7693 

.0338 
3.3961 

.0373 
4.2545 

.0365 

3.4867 

Sulphur   .... 
Moisture  .... 

.0089 
11.85 

6.525 

10.828 

4.5649 

12.3158 

ANALYSES  OF  SILICEOUS  ORES 


CONTENT 

MARQUETTE 
RANGE 

MENOMINEE 
RANGE 

VERMILION 
RANGE 

4227 

42  199 

51  1938 

Phosphorus     

.0316 

.0244 

.0498 

Silica     . 

35834 

34.141 

22.3642 

Sulphur      

.0099 

Moisture    

1.23 

2.2 

3.21 

Most  of  the  rich  ores  are  found  above  the  1000-foot 
level,  except  in  the  Mesabi  district  where  the  deposits  are 
shallow,  as  compared  with  their  horizontal  extent,  some, 
however,  being  over  400  feet  deep. 

In  the  early  period  of  mining  many  of  the  Lake  Superior 
bodies  were  worked  as  open  cuts,  but  with  depth  underground 
working  has  been  resorted  to.  There  are  many  deposits 
in  the  Mesabi  district  which  are  worked  as  open  pits  from 
which  the  granular  ore  is  dug  with  a  steam  shovel  and 
loaded  directly  on  to  the  ore  cars,  which  are  run  along  the 
working  face  (PI.  XVI). 

The  development  of  the  Lake  Superior  region  has  ad- 


PLATE  XVI 


IRON   OKES  265 

vanced  with  phenomenal  strides.  The  Marquette  range 
was  developed  as  early  as  1849,  and  the  Mesabi  as  late 
as  1892. 

The  total  yield  of  the  Lake  Superior  region  from  1850 
to  1902  was  246,558,896  long  tons.  Between  1891  and  1903 
it  was  191,646,959  long  tons,  or  77.75  per  cent  of  the  total 
amount  mined.  Van  Hise,  in  estimating  the  available  quan- 
tity of  high-grade  ore  still  in  the  ground,  believes  that 
even  if  it  approached  1,000,000,000  long  tons,  mining  at 
the  rate  of  20,000,000  tons  per  year  would  exhaust  the 
supply  in  the  first  half  of  the  twentieth  century.  Indeed, 
it  will  not  be  many  years  before  lower  grades  of  ore, 
hitherto  thrown  aside,  will  be  shipped  to  market.  Already 
ore  carrying  40  per  cent  iron,  but  low  in  phosphorus  and 
high  in  silica,  has  been  sold  for  mixing  in  with  high- 
grade  Mesabi  ores,  and  Van  Hise  believes  that  ores  below 
40  per  cent  in  iron  will  be  marketed  before  another 
generation. 

The  market  value  of  the  ores  is  based  on  the  iron  contents,  percentage 
of  water,  and  amount  of  phosphorus,  and  at  times  the  manganese  contents 
is  taken  into  consideration.  Some  objection  has  been  raised  in  the  last 
few  years  to  the  fine  character  of  the  Mesabi  ore  and  its  tendency  to  clog 
the  blast  furnace,  therefore  requiring  the  admixture  of  lump  ore  from 
the  other  ranges ;  but  this  objection  is  rapidly  disappearing,  and  some 
furnaces  now  use  over  75  per  cent  of  Mesabi  ore  in  their  charge. 

The  Lake  Superior  iron  ore  region  is  not  only  the  most  important  in 
the  world,  but  the  production  of  some  of  the  individual  mines  is  star- 
tling. This  enormous  output  can,  perhaps,  be  best  appreciated  by  some 
comparative  figures.  Thus,  for  example,  the  production  of  15,371,396 
long  tons  of  ore  mined  in  Minnesota  in  1903  is  about  three  quarters  of 
the  total  amount  extracted  from  the  famous  magnetite  deposits  of 
Cornwall,  Pennsylvania,  since  they  were  opened  in  1740,  or  of  the  total 


266          ECONOMIC   GEOLOGY   OP   THE  UNITED  STATES 

quantity  of  New  Jersey  magnetites  mined  since  they  were  first  worked  in 
1710.  The  production  even  of  single  mines  is  often  great,  six  mines  in 
1903  producing  over  1,000,000  long  tons  of  ore  each  (1  a). 

Clinton  Ore  (35,  36,  30). — This  ore,  which  is  also  called 
fossil,  pea,  or  dyestone  ore,  was  given  the  first  name  on 
account  of  the  ore  bed  having  been  originally  discovered  at 
Clinton,  New  York.  It  is  one  of  the  most  persistent  iron- 
ore  deposits  that  is  known,  for  it  occurs  wherever  rocks 
belonging  to  the  Clinton  stage  of  the  Silurian  are  found, 


f      e 

Fia.  50.  —  Section  Clinton  ore  beds,  Oxmoor,  Ala.  a,  red  sandstone,  5'; 
b,  yellow  sandstone,  6';  e,  red  sandstone,  15';  d,  ore,  22',  upper  2'  soft; 
e,  shale,  6' :  /,  rich  ore,  2'  6".  After  Smyth,  Amer.  Jour.  Sci.,  June,  1892. 

including  many  localities,  therefore,  along  the  line  of  the 
Appalachians  from  New  York  to  Alabama,  as  well  as  in 
Ohio  and  Wisconsin.  In  Pennsylvania  there  are  several 
belts  of  the  ore,  owing  to  the  presence  of  many  eroded  folds 
carrying  the  Clinton  rocks. 

The  ore  is  interstratified  with  sandstones  and  shales,  varies 
in  thickness  from  a  few  inches  to  ten  or  twenty  feet,  is  at 
times  oolitic  in  its  structure,  and  at  others  is  made  up  of  a 
mass  of  small  fossils.  At  Birmingham,  where  the  greatest 
development  has  occurred,  the  ore  occurs  in  a  ridge  known 
as  Red  Mountain,  the  bed  having  a  shale  roof  and  sandstone 


IRON  ORES  267 

floor,  while  the  thickness  of  the  main  bed  varies  from  twelve 
to  twenty  feet.  The  beds  dip  gently  to  the  east,  and  the 
iron  ore  is  worked  by  means  of  slopes,  although  the  early 
workings  at  some  of  the  mines  were  open  cuts,  on  account 
of  the  thin  overburden.  The  prominence  of  this  locality  is 
due  to  peculiar  conditions,  the  ore  being  bordered  on  the 
west  by  Cambrian  limestone  which  forms  the  valley  floor, 
while  on  the  western  side  of  the  valley  the  coals  of  the 
Warrior  Field  outcrop.  Thus  the  three  essential  elements 
for  iron  manufacture  are  brought  in  close  contact  by  folding 
and  faulting.  East  of  the  iron  range  are  two  additional 
coal  basins. 

The  great  development  of  this  ore  in  Alabama  is  due 
partly  to  favorable  local  conditions  and  partly  to  its  re- 
moteness from  the  Lake  Superior  region. 

The  origin  of  these  ore  bodies  has  been  argued  from 
different  standpoints,  some  holding  that  they  represent 
altered  limestone  beds  (35  a),  because  of  the  presence  of 
fossils  in  them,  while  the  concentric  nature  of  the  oolites, 
with  a  nucleus  of  worn  quartz  grains,  has  led  others,  espe- 
cially Smyth,  to  ascribe  a  concretionary  origin  (36)  to  them. 
The  former  theory  is  strengthened  by  finding  at  many 
places  an  increase  of  the  lime  contents  of  the  ore  with  the 
depth.  Thus  at  Attalla,  Alabama,  the  Clinton  limestone  at 
250  feet  from  the  surface  carries  only  7.75  per  cent  of  iron, 
while  at  the  outcrop  it  has  57  per  cent  of  iron. 

The  Clinton  iron  ores  usually  run  high  in  phosphorus  and  also  silica. 
Of  the  two  following  analyses,  No.  1  is  soft  ore  and  No.  2  hard  ore.  The 
latter  runs  higher  in  lime.  A  difference  also  appears  to  exist  between 
the  composition  of  the  fossil  or  upper  ore  bed  and  the  oolitic  or  lower 
ore  bed,  as  represented  by  analyses  3  and  4  (30)  of  the  following  table:  — 


268 


ECONOMIC   GEOLOGY   OF  THE  UNITED   STATES 


1 

2 

3 

4 

Fe    
Fe2O3    

52.87 

37.00 

30.24 

46.04 

p 

.43 

.37 

PoO. 

.75 

1.29 

S 

.11 

07 

sos  

SiO2  
A1A    
CaO 

13.66 
6.13 
1  26 

13.44 
3.18 
16  20 

.15 
8.71 
3.67 
20  64 

.20 
16.82 
3.54 
9.96 

MgO      
MnO 

.37 
30 

7.84 

3.41 

H20  
CO0 

1.62 

08 

.50 
12  24 

24  78 

13.62 

Other  Occurrences.  —  Extensive  deposits  of  hematite  in 
Carboniferous  limestone  are  found  in  Laramie  County,  Wyo- 
ming (1).  The  ore  carries  60  to  67  per  cent  iron,  2^  to  5  per 
cent  silica,  and  is  low  in  phosphorus.  In  New  Mexico,  near 
Hanover,  a  deposit  carrying  about  one  quarter  hematite  and 
three  quarters  magnetite,  along  the  contact  of  granite  and 
limestone,  is  also  extensively  worked.  Deposits  of  hematite 
in  brecciated  Carboniferous  limestones,  and  formed  proba- 
bly by  replacement,  are  known  in  Iron  and  Washington 
counties  of  southwestern  Utah,  and  are  probably  the  largest 
iron-ore  deposits  in  the  West.  Other  deposits  are  found 
in  the  Wasatch  Mountains,  along  the  contact  of  andes- 
ite  and  limestone.  The  ore  here  consists  of  hard  black 
crystallized  hematite  and  magnetite,  associated  with  chal- 
cedony and  crystalline  quartz.  Leith  (32)  considers  it  to  be 
a  replacement  deposit.  While  much  of  the  ore  is  of  good 
quality,  it  is  mostly  non-Bessemer.  The  Utah  deposits  are 


IRON    ORES  269 

at  present  too  far  from  the  railroad  to  be  of  much  value, 
but  are  to  be  looked  on  as  an  important  future  source  of 
supply.  Specular  hematites  also  occur  at  Pilot  Knob,  Mis- 
souri, interstratified  with  breccias  and  porphyry  sheets,  and 
were  formerly  much  worked. 

LIMONITE 

Limonite  (41-52)  or  brown  hematite  is,  like  magnetite,  of 
comparatively  little  importance  in  the  United  States  as 
compared  with  hematite,  having  yielded  an  average  of  but 
12.2  per  cent  of  the  total  iron  production  of  the  United 
States  in  the  last  fifteen  years,  and  but  8.8  per  cent  of  the 
total  domestic  iron  ore  production  in  1903. 

Although  deposits  of  limonite  are  widely  scattered  over 
the  United  States,  about  nine  tenths  of  the  total  quantity 
comes  from  the  deposits  located  in  western  New  England 
and  the  Appalachian  belt. 

Owing  to  their  mode  of  origin,  limonites  are  rarely  of 
high  purity,  being  commonly  associated  with  more  or  less 
ferruginous  clay,  which  has  to  be  separated  from  the  ore  by 


Limonite  may  occur  under  a  variety  of  conditions  and 
associated  with  different  kinds  of  rocks,  but  two  impor- 
tant types  are  recognized,  viz.  bog  ores,  and  residual 
limonites. 

Bog  Ores.  —  The  bog  ores  are  formed  by  the  precipitation  of 
limonite  in  swamps,  ponds,  or  lakes.  The  iron  is  dissolved 
from  the  rocks  or  soil  by  percolating  waters  charged  with 
carbon  dioxide  or  organic  acids,  either  in  the  form  of  ferrous 
carbonate  or  ferrous  sulphate.  As  these  iron-bearing  waters 


270 


ECONOMIC   GEOLOGY   OF   THE   UNITED   STATES 


discharge  into  the  ponds  the  iron  compounds  are  oxidized 
to  hydrous  ferric  oxide  or  limonite,  which  settles  on  the 
bottom.  Such  ores  are  usually  impure  from  an  admixture  of 
sand  or  clay  which  has  been  deposited  at  the  same  time,  and 
are  rarely  of  any  thickness.  They  are  of  no  commercial 
value  in  the  United  States,  but  in  foreign  countries  are 
worked  in  Sweden,  in  which  kingdom  they  have  been  known 
to  accumulate  in  ponds  to  the  depth  of  18  inches  or  more 
every  15  to  30  years.  The  ore  is  collected  periodically 
by  dredging.  Bog  ore  is  also  obtained  in  Quebec,  Can. 

Residual  limonites. — The  residual  limonites  are  a  much 
more  important  class,  and   form  (1)  by  the  weathering  of 


Fio.  51.  — Section  illustrating  formation  of  residual  limonite  in  limestone.    After 
Hopkins,  Geol.  Soc.  Amer.,  Bull.  XI :  485. 

pyritiferous  veins  (see  gossan,  Chapter  XIII),  or  (2)  more 
often  from  the  weathering  of  ferruginous  rocks.  The  sec- 
ond process  results  in  the  formation  of  deposits  of  iron- 
stained  clay  scattered  through  which  are  nodules  and 
irregularly  shaped  masses  of  limonite,  these  making  up 
from  5-10  per  cent  of  the  entire  mass. 

The  limonite  may  accumulate  first  by  deposition  in  the 
cracks  of  the  rock,  or  by  impregnation  or  replacement,  and 
prior  to  the  breaking  down  of  the  rock  to  a  mass  of  residual 
clay.  Since  these  deposits  often  represent  the  concentra- 
tion of  iron  from  a  great  thickness  of  rock,  it  is  not 


PLATE  XVII 


Fio.  1.  — Pit  of  residual  limonite,  Shelby,  Ala.     After  McCalley,  Ala.  Geol.  Surv. 
Report  on  Valley  Regions,  Pt.  II:  11,  1897. 


FIG.  2.  —  Old  limonite  pit,  Ivanhoe,  Va.,  showing  pinnacled  surface  of  limestone 
which  underlies  the  ore-bearing  clay.  The  level  of  surface  before  mining 
began  is  seen  on  either  side  of  excavation.  H.  Ries,  photo. 


IRON   OEES  271 

necessary  that  the  parent  material  contain  a  high  percentage 
of  iron. 

An  important  belt  of  residual  limonites  of  Cambro-Silurian 
age,  and  associated  with  slates,  schists,  or  limestone,  is  found 
extending  from  Vermont  to  Alabama,  along  the  Great  Valley, 
and  consisting  of  beds  of  residual  clay  carrying  limonite 
nodules  (42,  44-48 a).  This  type  of  deposits  is  worked  from 
Vermont  to  Alabama,  and  some  of  the  larger  mines  in  the 
latter  state  have  an  annual  production  of  over  100,000  tons. 
Those  found  in  Georgia  are  associated  with  manganese. 
Plate  XVII,  Fig.  2,  shows  the  irregular  surface  of  the 
Cambro-Silurian  limestone  in  one  of  the  Virginia  pits. 

In  addition  to  these,  important  deposits  are  found  in  Vir- 
ginia, representing  the  weathered  portion  of  a  great  belt  of 
pyrite  bodies.  This  extends  for  over  20  miles  and  is  known 
as  the  "Great  Gossan  Lead,"  its  contents  averaging  from 
40  to  41  per  cent  metallic  iron  (48  J,  see  also  Copper,  Duck- 
town,  Tennessee). 

The  Oriskany  formation  also  carries  large  deposits  of 
limonite  to  the  westward  of  the  Cambro-Silurian  belt,  and 
these  are  actively  worked  in  Virginia  (49). 

Other  Occurrences. — Limonites  of  more  or  less  distinctly 
bedded  character  are  found  in  the  Tertiary  of  northeastern 
Texas  (50,  52),  where  they  occur  as  thin  beds  capping  the  hills 
and  are  mined  for  local  use  (50).  Others  are  found  at  the  same 
horizon  in  Arkansas  but  promise  to  be  of  little  commercial 
value.  In  the  former  case  they  are  closely  associated  with 
greensands,  and  may  have  formed  by  weathering  either  from 
these  or  from  pyrite  grains.  Small  deposits  are  known  in 
Iowa  (41),  Wisconsin,  Minnesota,  and  Oregon  (3  a).  Much 
limonite,  at  times  manganiferous  and  containing  even  small 


272 


ECONOMIC  GEOLOGY  OF  THE  UNITED  STATES 


quantities  of  silver,  is  obtained  from  the  gossan  of  the  Lead- 
ville  ore  bodies.     Its  chief  use  is  as  a  flux. 

The  following  analyses  give  the  composition  of  limonites 
from  several  localities. 

ANALYSES  OF  LIMONITES 


Fe 

P 

8 

SiO, 

AliOs 

CaO 

MgO 

H»0 

Moist. 

MnO, 

Average  composition  Alabama 

limonite   

48.54 

.38 

.O'J 

11.22 

8.61 

.84 

6.00 

7.00 

Average  of  29  commercial 

P,0B 

analyses,  Pa.,  Cambro-Silurian 

43.4T 

1.10 

.06 

18.9T 

2.39 

.48 

.42 

11.62 

2.85 

ores      

SO, 

Rusk,  Cherokee  Co.,  Texas   .    . 

44.68 

.09 

.20 

ttM 

"5776^ 

-48 

Tr 

11.03 

Allamakee  County,  la.      ... 

54.32 

1.8 

— 

Those  of  the  Appalachian  belt  are  much  used  by  pig-iron 
manufacturers  because,  owing  to  their  siliceous  character, 
they  can  be  mixed  in  with  high-grade  Lake  Superior  ores 
which  are  deficient  in  silica.  They  are  also  cheaper,  and 
their  mixture  with  other  ores  seems  to  facilitate  the  reduc- 
tion of  the  iron  in  the  furnace. 


SIDERITE 

Siderite  (53-58)  is  the  least  important  of  all  the  ores  of 
iron  mined  in  the  United  States,  both  on  account  of  the 
small  quantity  and  its  low  iron  contents.  When  of  con- 
cretionary structure,  with  clayey  impurities,  it  is  termed 
clay  ironstone,  and  these  concretions  are  common  in  many 
shales  and  clays.  In  some  districts  siderite  forms  beds, 
often  several  feet  in  thickness,  but  containing  much  bitumi- 
nous and  argillaceous  matter,  and  known  as  blackband  ore. 
This  is  found  in  many  Carboniferous  shales. 


IKON   ORES  273 

Eastern  Ohio  (54)  and  Kentucky  (53)  and  western  Penn- 
sylvania (55)  are  the  most  important  producing  states.  The 
ore  is  obtained  chiefly  from  the  Lower  Coal  measures, 
although  known  in  the  other  stages  of  the  Pennsylvania 
series.  Another  important  occurrence  is  at  the  Burden 
Mines,  near  Hudson,  New  York  (56),  where  lens-shaped 
beds  of  clay  ironstone  are  found  in  the  Hudson  River 
shales  and  sandstones.  The  beds  have  been  folded  and 
faulted,  so  that  the  ore  bodies  lie  in  basins.  The  ores 
are  rather  magnesian,  and  on  this  account  it  has  been 
suggested  by  Kimball  that  they  have  been  formed  in  shore 
waters  receiving  drainage  from  the  Archaean  Highlands ; 
they  are  also  high  in  phosphorus.  Siderite  is  of  far  greater 
importance  in  foreign  countries,  and  large  quantities  are 
shipped  to  the  United  States  from  Spain.  It  is  roasted 
for  use,  thereby  expelling  the  carbonic  acid  and  raising 
the  iron  contents. 

Production  of  Iron  Ores.  —  The  iron  ore  mining  industry 
in  the  United  States  has  progressed  with  phenomenal 
strides,  and  this  country  now  leads  the  world  in  the  pro- 
duction of  iron  ore.  Indeed,  so  great  has  the  production 
become  that  in  1903  it  was  equal  to  the  combined  output 
of  Germany  and  Luxemburg  and  the  British  Empire  for 
1902.  Moreover,  the  average  iron  content  of  the  ore 
mined  in  the  United  States  is  higher  than  that  mined 
in  foreign  countries,  thereby  resulting  in  the  production 
of  a  greater  amount  of  pig  iron  from  a  given  quantity  of 
ore. 

The  Lake  Superior  region  is  now  producing  at  least  three 
quarters  of  the  iron  ore  used  in  the  United  States,  and  it 


274 


ECONOMIC   GEOLOGY   OP   THE   UNITED   STATES 


has  much  the  largest  reserves  of  high-grade  ores,  but  even 
these  may  be  exhausted  in  fifty  years  or  less  at  the  present 
rate  of  consumption.  The  low-grade  ores  of  this  region 
and  others  will,  however,  be  available  for  a  much  longer 
time. 

While  there  is  not  danger  of  the  present  supply  of 
ore  soon  becoming  exhausted,  still  with  the  present  con- 
sumption it  is  well  to  consider  possible  sources  of  the 
future. 

In  the  United  States  the  Utah  and  some  other  western 
deposits  will  no  doubt  be  drawn  upon,  and  many  ores  now 
looked  upon  as  too  low  grade  to  work  will  also  be  con- 
sidered. Aside  from  domestic  sources  of  supply  there  are 
foreign  ones  which  may  perhaps  be  eventually  turned  to, 
such  as  those  from  Canada,  Newfoundland,  and  Brazil  on 
this  side  of  the  Atlantic,  or  even  those  of  Scandinavia  on  the 
European  side.  In  the  last-mentioned  country  especially 
attention  has  been  drawn  in  the  last  few  years  to  mag- 
netite deposits  located  well  within  the  Polar  circle  and  of 
stupendous  size. 

The  production  of  iron  ores  in  the  United  States  from 
1889  to  1903  was  as  follows :  — 

TOTAL  PRODUCTION  OF  IRON  ORES  IN  THE  UNITED  STATES 


YEAR 

LONG  TONS 

YEAR 

LONG  TONS 

1889 

14,518,041 

1895 

15,957,614 

1890 

16,036,043 

1896 

16,005,449 

1891 

14,591,178 

1897 

17,518,046 

1892 

16,296,666 

1898 

19,433,716 

1893 

11,587,629 

1899 

24,683,173 

1894 

11,879,679 

1900 

27,553,161 

IRON   ORES 


275 


PRODUCTION  OF  IRON  ORE  IN  THE  MORE  IMPORTANT  STATES  FROM 
1901  TO  1903 


1901 

LONG  TONS 

1902 

LONG  TONS 

1903 

LONG  TONS 

11  109  537 

15  137  650 

15  371  396 

9  654  067 

11  135  215 

10  600  330 

2,801,732 

3,574,474 

3,684,960 

789  494 

874  542 

85->  704 

Virginia  and  West  Virginia  .  . 

925,394 
738  868 

987,958 
783  996 

801,161 
675,053 

1,040,684 

822,932 

644,599 

New  York 

420  218 

555  321 

540  460 

401  989 

441  879 

484  796 

215,599  l 

364,890  2 

443,452 

Other  states  

789,897 

875,278 

920,397 

Total  

28,887,479 

35,554,135 

35,019,308 

PRODUCTION  OF  LAKE  SUPERIOR  IRON  ORES  BY  RANGES 


RANGE 

1901 
LONG  TONS 

1902 

LONG  TONS 

1903 

LONG  TONS 

3  041  869 

3  683  792  8 

3  422  341 

3  597  089 

3  734  712 

3  686  214 

3  697  408 

4  421  250  8 

4  093  320 

Mesabi  

9,303,541 

13,080,118 

13,452,812  8 

1  805  996 

2  057  532  3 

1  918  584 

PRODUCTION  OF  MOST  IMPORTANT  IRON-ORE   PRODUCING  COUNTRIES 


COUNTRY 

YEAR 

QUANTITY 
LONG  TONS 

PERCENTAGE 
WORLD'S 
PRODUCTION 

United  States 

1903 

35  019  308 

3471 

Germany  and  Luxemburg    . 
Great  Britain  

1903    . 
1903 

21,230,639 
13  715  645 

21.04 
1359 

1903 

8  478  600 

840 

Russia  and  Finland.     .     .     . 
France    

1902 
1902 

5,648,227 
5  003  782 

5.60 
496 

1903 

3  677  841 

3  65 

Austria-Hungary     .... 

1902 

3,329,128 

3.30 

Includes  North  and  South  Carolina. 

3  Maxima. 


2  Includes  North  Carolina. 


276          ECONOMIC   GEOLOGY   OF   THE   UNITED   STATES 

The  exports  of  iron  ore  from  the  United  States  in  1903 
amounted  to  80,611  long  tons,  valued  at  $255,728. 


REFERENCES  ON  IRON  ORES 

GENERAL.  1.  Birkenbine,  Chapters  on  Iron  Ores  in  Mineral  Resources  of 
United  States,  published  annually  by  U.  S.  Geol.  Survey ;  1  a.  Mining 
Census,  1902,  Mines  and  Quarries.  2.  Kimball,  Amer.  Geol.,  XXI : 
155,  1898.  (Concentration  by  weathering.)  3.  Penrose,  Jour. 
Geol.,  1 :  356,  1893.  (Chemical  relations  of  iron  and  manganese.) 
3  a.  Pumpelly,  Tenth  Census,  XV.  4.  Swank,  Eng.  and  Min.  Jour., 
LXXIII :  347,  1902.  (U.  S.  iron  and  steel  works.)  5.  Winchell, 
Amer.  Geol.,  X :  277,  1892.  (Theories  of  origin.) 

STATE  REPORTS.  6.  Chauvenet,  Amer.  Inst.  Min.  Engrs.,  Trans.  XVIII : 
266,  1890.  (Colo.)  7.  Nason,  Mo.  Geol.  Surv.,  II,  1892.  (Mo.) 
8.  Nitze,  N.  Ca.  Geol.  Surv.,  Bull.  I,  1893.  (N.  Ca.)  9.  Orton, 
Ohio  Geol.  Surv.,  V:  371, 1884.  (Ohio.)  10.  Putnam,  10th  Census, 
XV  :  469.  (U.S.)  11.  Shaler,  Ky.  Geol.  Surv.,  New  Series,  III :  163, 
1877.  12.  Smock,  N.  Y.  State  Museum,  Bull.  7,  1889.  (N.  Y.) 
13.  Van  Hise,  U.  S.  Geol.  Surv.,  21st  Ann.  Rept.,  Ill:  305,  1901. 
(Lake  Superior  region.)  14.  Winchell,  Minn.  Geol.  Surv.,  Bull.  6, 
1891.  (Minn.). 

SPECIAL  PAPERS.  Magnetite.  15.  D'Invilliers,  Second  Pa.  Geol.  Surv., 
D3,  II,  pt.  1 :  237,  1883.  (Berks  Co.)  16.  Prime,  Ibid.  1 :  190, 
1883.  (Lehigh  Co.)  17.  D'Invilliers,  Amer.  Inst.  Min.  Engrs., 
Trans.  XIV:  873,  1886.  (Cornwall.)  18.  Hulst,  Eng.  and  Min. 
Jour.,  LXXVIII :  350,1904.  (Titaniferous  ores.)  18  a.  Keith,  U.S. 
Geol.  Surv.,  Bull.  213 :  243,  1903.  (N.  Ca.)  19.  Kemp,  Amer. 
Inst.  Min.  Engrs.,  Trans.  XXVII:  146,  1898.  (Mineville,  N.Y.) 
20.  Kemp,  U.S.  Geol.  Surv.,  19th  Ann.  Rept.,  Ill:  377,  1899. 
(Adirondack  titaniferous  ores.)  21.  Kemp,  S.  of  M.  Quart.,  XX : 
323, 1899.  (Titaniferous  magnetites.)  22.  Nason,  Amer.  Inst.  Min. 
Engrs.,  Trans.  XXIV :  505,  1895.  (N.  J.)  23.  Spencer,  Min.  Mag., 
X :  377,  1904.  (N.J.)  24.  Wolff,  N.  J.  Geol.  Surv.,  Ann.  Rept.  for 
1893 :  359,  1894.  (N.J.) 

Hematite.  25.  Bayley,  U.  S.  Geol.  Surv.,  Mon.  XLVI,  1904.  (Menomi- 
nee  range.)  26.  Boutwell,  U.  S.  Geol.  Surv.,  Bull.  225:  221,  1904. 
(Uinta  Mts.,  Utah.)  27.  Clements,  Smythe,  Bayley,  and  Van  Hise, 
U.  S.  Geol.  Surv.,  19th  Ann.  Rept.,  Ill:  1,  1899.  (Crystal  Falls 
district.)  28.  Clements,  U.  S.  Geol.  Surv.,  Mon.  XLV,  1903.  (Ver- 
milion range.)  29.  Dewees,  Second  Pa.  Geol.  Surv.,  Rept.  F,  1878. 
(Pa.)  30.  Eckel,  Eng.  and  Min.  Jour.,  LXXIX  :  897, 1905.  31.  Leith, 


IKON  ORES  277 

U.  S.  Geol.  Surv.,  Mon.  XLIII,  1903.  (Mesabi  range.)  32.  Leith, 
U.  S.  Geol.  Surv.,  Bull.  225 :  229,  1904.  (S.  Utah.)  33.  McCreath, 
Second  Pa.  Geol.  Surv.,  MM :  229, 1879.  (Many  analyses.)  34.  Pechin, 
Amer.  Inst.  Min.  Engrs.,  Trans.  XIX :  1016, 1891.  (Va.)  35.  Porter, 
Amer.  Inst.  Min.  Engrs.,  Trans.  XV:  170,  1887.  (Tenn.,  Ala.,  Ga.) 
35 a.  Russell,  U.S.  Geol.  Surv.,  Bull.  52:  22,  1889.  (Clinton  ore.) 
36.  Smyth,  Amer.  Jour.  Sci.,  XLIII :  487,  1892  (Clinton  ore)  ;  and 
N.  Y.  State  Geologist,  22d  Ann.  Kept.,  1902 :  116, 1904.  37.  Van  Hise, 
U.  S.  Geol.  Surv.,  21st  Ann.  Kept.,  Ill :  305,  1901.  (Lake  Superior 
region.)  37  a.  Van  Hise,  Bay  ley  and  Smyth,  U.  S.  Geol.  Surv.,  Mon. 
XXVIII,  1897.  (Marquette.)  38.  Van  Hise  and  Irving,  U.  S.  Geol. 
Surv.,  Mon.  XIX,  1892.  (Penokee-Gogebic  range.)  39.  Weidman, 
Wis.  Geol.  and  Nat.  Hist.  Surv.,  Bull.  13,  1904.  (Baraboo  district, 
Wis.)  40.  Woodbridge,  Series  of  articles  on  Mesabi  range,  Eng.  and 
Min.  Jour.,  1905. 

Limonite.  41.  Calvin,  la.  Geol.  Surv.,  IV :  97,1895.  (la.)  42.  Cat- 
lett,  Amer.  Inst.  Min.  Engrs.,  Trans.  XXIX  :  308,  1900.  (Va.) 
43.  Diller,  U.  S.  Geol.  Surv.,  Bull.  213  :  219,  1903.  (Redding  quad- 
rangle, Calif.)  44.  Eckel,  Eng.  and  Min.  Jour.,  LXXVIII :  432, 
1904.  (E.  N.  Y.  and  W.  New  Eng.)  45.  Garrison,  Eng.  and  Min. 
Jour.,  LXXIII :  258,  1904.  (Chemical  characteristics.)  46.  Hayes, 
Amer.  Inst.  Min.  Engrs.,  Trans.  XXX :  403,  1901.  (Ga.)  47.  Hayes 
and  Eckel,  U.  S.  Geol.  Surv.,  Bull.  213  :  233,  1903.  (Cartersville,  Ga.) 
48.  Hopkins,  Geol.  Soc.  Amer.,  Bull.  XI :  475, 1 900.  (Pa.)  48  a.  Mc- 
Calley,  Ala.  Geol.  Surv.,  Report  on  Valley  Region,  II,  1897.  (Ala.) 
48  b.  Moxham,  Amer.  Inst.  Min.  Eng.,  Trans.  XXI :  133.  (Great 
Gossan  Lead.)  49.  Pechin,  Eng.  and  Min.  Jour.,  LIV:  150,  1892. 
(Va.  Oriskany  ores.)  50.  Penrose,  Geol.  Soc.  Amer.,  Bull.  Ill :  44, 
1892  (Ark.  and  Tex.  Tertiary  ores);  also  Ark.  Geol.  Surv.,  Rep. 
1892,  vol.  1,  1892.  51.  Phillips,  Bug.  and  Min.  Jour.,  LXV :  489, 
1898.  (Ala.)  52.  Walker,  Tex.  Geol.  Surv.,  2d  Ann.  Rept.,  291, 
1891.  (Cherokee  Co.,  Texas.) 

Siderite.  53.  Moore,  Ky.  Geol.  Surv.,  2d  Ser.,  I,  pt.  3  :  63,  1876.  (Ky.) 
54.  Orton,  Ohio  Geol.  Surv.,  V :  378, 1884.  (Ohio.)  55.  Second  Pa. 
Geol.  Surv.,  K:  386,  and  MM:  159,  1879.  (Pa.)  56.  Raymond, 
Amer.  Inst.  Min.  Engrs.,  Trans.  IV :  339, 1876.  (N. Y.)  57.  Smock, 
N.  Y.  State  Museum,  Bull.  7 :  62,  1889.  (N.Y.) 


CHAPTER  XV 


COPPER 

Ores  of  Copper.  —  Copper-bearing  minerals  are  not  only 
numerous,  but  widely  although  irregularly  distributed. 
More  than  this,  copper  is  found  associated  with  nearly 
every  variety  of  ore  or  ore  deposit.  Nevertheless  but  few 
minerals  serve  as  ores  of  copper,  and  the  same  may  be  said 
regarding  the  number  of  important  producing  districts  in  the 
United  States. 

The  ores  of  copper  together  with  their  theoretic  composi- 
tion are  as  follows  :  — 


ORE 

COMPOSITION 

Cu 

S 

Fe 

Cu 

100 

Chalcocite   

Cu0S 

79.8 

20.2 

CuFeS 

345 

350 

305 

(Copper  pyrite) 

CuoFeS 

555 

281 

164 

Covellite       

CuS 

6648 

33.52 

Tetrahedrite     .... 

4  Cu2S  Sb  S3 

52.1 

23.10 

1  39 

Enargite  

Cu3AsS4 

48.40 

32.50 

Melaconite  (Black  oxide) 

CuO 
Cu  O 

79.86 

8880 

Azurite    

3  CuO,  2  CO2+H20 

55.00 

(Blue  carbonate) 
Malachite     

2  CuO  CO2  H2O 

57.40 

(Green  carbonate) 
Chrysocolla  

CuO,  SiO2,  2  H2O 

36.10 

278 


COPPER  279 

Very  few  ores  approach  the  theoretic  percentages  given 
above.  Thus  in  Michigan,  where  native  copper  is  the  ore 
mineral,  this,  as  now  mined,  rarely  averages  above  1  per 
cent  metallic  copper.  At  Butte,  Montana,  the  copper-bear- 
ing minerals  are  chalcocite,  enargite,  bornite,  and  chalco- 
pyrite,  but  much  of  the  ore  does  not  usually  contain  more 
than  5  or  6  per  cent  metallic  copper,  and  in  rarer  instances 
12  per  cent.  The  same  holds  true  in  many  other  regions. 
At  the  present  time  chalcopyrite  is  probably  the  most  widely 
distributed  of  all  the  copper  ores,  and  the  one  most  often 
worked,  but  it  is  not  the  prominent  ore  in  the  largest  pro- 
ducing districts. 

Copper  ores  are  found  in  many  formations,  ranging  from 
the  pre-Cambrian  to  the  Tertiary,  but  grouped  according  to 
their  mode  of  origin  they  fall  mostly  into  one  of  the  four 
following  groups  (2)  :  — 

1.  Magmatic  segregations.     No  workable  deposits  of  this 
type  are  known  in  the  United  States. 

2.  Contact  metamorphic  deposits,  in  crystalline,  usually 
garnetiferous  limestone,  along  igneous  rock  contacts.     The 
copper  is  thought  to  have  been  introduced  by  vapors  from 
the  igneous  rock. 

3.  Deposits  formed   by  ascending,  circulating,  probably 
hot  waters,  the  ores  being  deposited  in  fissures,  pores,  spaces 
of  brecciation,  or  sometimes  by  replacement  of  the  rock. 

4.  Pod  or  lens-shaped  deposits  in  crystalline  schists,  which 
may  represent  concentration  of  material  from  a  disseminated 
condition  in  the  surrounding  rocks. 

While  the  third  and  fourth  groups  include  all  the  largest 
deposits  of  the  world,  still  these  do  not  in  all  cases  owe  their 
economic  importance  to  the  mode  of  formation,  but  rather  to 


280          ECONOMIC   GEOLOGY   OF   THE  UNITED   STATES 

secondary  changes  which  have  taken  place  in  them,  resulting 
in  a  leaching  of  the  copper  in  the  upper  part  of  mass,  as 
copper  sulphate,  and  its  transference  to  lower  levels,  where 
it  is  redeposited  through  the  influence  of  copper  sulphide, 
iron  compounds,  or  limestone. 

Impurities  in  Copper  Ores.  —  The  impurities  which  copper 
ores  may  contain  are  iron,  silver,  antimony,  arsenic,  tellurium, 
silica,  sulphur,  and  phosphorus,  and  in  the  metallurgical  treat- 
ment of  the  ore  it  is  desirable  to  rid  the  metal  of  these  as 
fully  as  possible.  Both  iron  and  silver  may  affect  the  elec- 
trical conductivity  of  copper,  and  antimony  and  arsenic  do 
so  to  a  smaller  extent. 

Tellurium  is  not  uncommon  in  some  districts,  and  renders 
the  metal  red-short  even  in  small  amounts.  Silver,  even 
if  present  in  as  small  amounts  as  .5  per  cent,  lowers  the 
electrical  conductivity,  and  above  3  per  cent  affects  the 
toughness  and  malleability  of  the  copper.  Sulphur  up  to 
.25  per  cent  lowers  the  malleability  and  .5  per  cent  renders 
the  metal  cold-short,  while  .4  or  more  per  cent  phosphorus 
makes  it  red-short. 

Many  low-grade  ores  can  be  concentrated  by  crushing  and 
mechanical  concentration,  as  in  the  Lake  Superior  district  of 
Michigan  and  at  Butte,  Montana.  Sulphide  ores  may  also 
be  given  a  preliminary  roasting  to  get  rid  of  the  volatile 
sulphur,  arsenic,  etc.  The  ore  is  then  usually  put  through 
a  smelting  process,  followed  sometimes  by  electrolytic  treat- 
ment for  refining  the  metal. 

Superficial  Alteration  of  Copper  Ores  (see  25,  ore  deposits). 
—  This  may  produce  results  of  great  economic  importance, 
and  excellent  examples  of  it  are  seen  in  some  of  the  Arizona 


COPPER  281 

deposits,  where  the  upper  portions  of  the  copper  deposits  are 
brown  or  black  ferruginous  porous  masses  brightly  colored 
with  oxidized  copper  minerals  such  as  cuprite,  malachite, 
azurite,  and  chrysocolla,  while  below  this  at  a  variable  depth 
they  pass  into  sulphides. 

In  weathering,  the  copper  minerals,  such  as  chalcopyrite 
or  other  sulphides,  are  usually  oxidized  first  to  sulphates, 
and  subsequently  changed  to  oxides,  carbonates,  or  silicates 
and  occasionally  even  to  chlorides  and  bromides.  A  con- 
centration of  the  ore  deposit  may  take  place  partly  by  segre- 
gation and  partly  by  leaching,  and  pockets  of  the  ore  form, 
which  are  surrounded  by  oxidized  iron  minerals  forming 
part  of  the  gangue. 

While  the  oxidation  will  not  increase  the  total  copper 
contents  of  the  ore  body,  still  it  may  change  it  into  a  more 
concentrated  form,  for  the  carbonates  and  other  oxidized 
copper  minerals  contain  more  copper  than  the  original  sul- 
phide. The  ore  in  the  gossan  may  therefore  run  from  8  to  30 
per  cent  or  more,  while  below  it  may  show  only  5  per  cent  of 
copper  (see  25,  ore  deposits).  These  altered  ores  cannot  how- 
ever be  more  cheaply  treated.  If  leaching  follows  oxidation, 
the  gossan  may  be  freed  of  its  ore,  as  at  Butte,  Montana, 
where  the  upper  part  of  the  ore-bearing  fissures  is  poor 
siliceous  gangue.  Secondary  enrichment  may  also  occur 
below  the  water  level,  giving  chalcocite,  chalcopyrite,  and 
bornite  of  later  origin.1 

Distribution  of  Copper  Ores  in  the  United  States. — About 
90  per  cent  of  the  copper  produced  in  the  United  States  is 
obtained  from  three  states,  viz.,  Montana,  Michigan,  and 
Arizona,  named  in  the  order  of  their  output,  the  rest  coming 

1  Both  chalcopyrite  and  bornite  are  more  often  regarded  as  primary 
sulphides. 


282          ECONOMIC   GEOLOGY  OP   THE   UNITED   STATES 

from  the  Appalachians  and  Cordilleran  area ;  the  ores  of  the 
latter  are  often  worked  chiefly  for  their  gold  contents,  with 
copper  as  a  secondary  product. 

Montana.  —  The  mining  camp  of  Butte  (29-31),  which  is 
not  only  the  greatest  producer  of  copper  in  the  world,  but 
in  which  one  mine,  the  Anaconda,  yields  one  seventh  of  the 
entire  world's  supply,  lies  in  the  central  part  of  the  Rocky 


FIG.  52. —  Map  showing  distribution  of  copper  ores  in  United  States.    Adapted 
from  Ransome,  Min.  Mag.,  X:  1. 

Mountain  region.  The  ore-bearing  veins  occur  in  an  older 
hornblendic  granite,  known  as  the  Butte  granite,  found  chiefly 
in  the  eastern  part  of  the  district,  and  which  is  cut  by  the 
acid  Bluebird  granite  or  aplite,  that  forms  dikes  and  small 
masses  in  this  region.  Both  of  these  granites  are  intersected 
by  dikes  of  quartz  porphyry  of  doubtful  genetic  relation  to 
the  ore  bodies,  although  the  latter  are  usually  low-grade 
when  bounded  by  either  the  porphyry  or  the  aplite.  The 
last  stage  of  igneous  activity  consisted  of  the  extrusion  of 


COPPER 


Pair-  ALLUVIUM  AND  WASH  PLEISTOCENE 

t;;  ;J  Nrl  -  INTRUSIVE  RHVOL'ITE  NEOCENE 

Oft-    APLITE 


•  POST  CARBONIFEROUS 


GRANITE 


Fia.  53.  — Map  of  Butte,  Mont.,  district  showing  distribution  of  veins  and  geology. 
After  Weed,  U.  S.  Geol  Surv.,  Atlas  Folio. 


284 


ECONOMIC   GEOLOGY   OF  THE   UNITED   STATES 


rhyolite  flows  and  ash  beds,  and  dikes  of  the  same  rock  also 
cut  the  silver  veins  of  the  region. 

The  Butte  district  contains  both  silver  and  copper  veins. 
The  latter  are  found  in  an  area  about  a  mile  long  and  one 

half  mile  wide,  in  the  south- 
eastern part  of  the  district, 
while  the  silver  veins  sur- 
rounding it  are  of  much  less 
importance. 

The  granites  are  traversed 
by  several  systems  of  joints 
and  shear  planes,  and  the  ore 
has  not  only  been  deposited 
in  them,  but  has  replaced 
the  wall  rock  as  well.  The 
veins  are  of  varying  age,  the 
larger  and  richer  ones  hav- 
ing been  broken,  reopened, 
and  even  displaced  by  fault- 
ing, and  a  careful  study  of 
the  district  has  shown  four 
separate  periods  of  fracture, 
in  three  of  which  ores  have 
been  formed. 

In  the  earliest,  the  vein 
filling,  which  was  the  result 
of  replacement  in  sheeted  granite,  is  quartz  and  pyrite  with 
some  copper.  Later  fracturing  produced  large  masses  of 
crushed  granite,  clay,  etc.,  with  boulders  of  ore,  and  this 
was  sometimes  added  to  by  the  deposition  of  enargite  by 
later  ascending  solutions.  The  richest  masses  or  bonanzas 


QUARTZ  PORPHYRY 


a.  OXIDIZED  ZONE 
6.  CHALCOCITE 
C.  ENARGITE 

d.  PYRITE 

e.  QUARTZ 
/.  BORNITE 

a.  CHALCOCITE 


I 1  FAULT 

FIG.  M.  —  Section  at  Butte,  Mont.,  show- 
ing mode  of  occurrence  of  ore. 
After  Winchell,  Eng.  and  Min. 
Jour.,LXXVIII:-7. 


PLATE  XVIII 


COPPER  285 

of  glance  found  in  some  of  the  mines  are  of  secondary 
origin. 

While  the  veins  exhibit  a  curious  uniformity  of  direction, 
most  of  them  striking  nearly  east  and  west,  and  few  of  them 
departing  more  than  15°  to  20°  from  the  vertical,  still  they 
show  considerable  variation  in  width,  ranging  from  a  few 
feet  to  50,  or  even  150  where  the  altered  country  rock  is 
impregnated  with  glance.  Unfortunately,  the  complexity  of 
the  veins  and  uncertainty  of  boundaries  has  given  rise  to 
much  costly  litigation  in  the  district. 

The  common  vein  minerals  are  quartz,  pyrite,  and  chalco- 
cite.  Bornite  and  enargite  are  locally  important,  while 
chalcopyrite  and  covellite  are  known.  Present  in  sub- 
ordinate quantities  are  tetrahedrite,  tennantite,  and  argen- 
tite.  The  chalcocite  is  always  of  secondary  character. 

The  average  composition  of  first-class  ore  in  Butte  in 
1902  was:  Cu,  11.4  per  cent;  Fe,  16.6  per  cent;  Zn,  .3  per 
cent;  S,  22.6  per  cent;  As  and  Sb,  1.4  per  cent;  A12O3,  7.9 
per  cent;  insoluble,  44.7  per  cent;  SiO2,  38.2  per  cent;  Ag, 
oz.  5.2;  Au,  oz.  .04.  Second-class  ore  averages:  Cu,  5.2 
per  cent ;  Fe,  16  per  cent ;  S,  19.8  per  cent ;  insoluble, 
56  per  cent;  Ag,  3  oz. 

Gold  is  quite  universally  distributed  through  the  ores, 
though  in  very  small  amounts,  forming  3  per  cent  of  the 
values  in  the  copper  bullion.  Small  amounts  of  arsenic,  anti- 
mony, bismuth,  tellurium,  selenium,  and  nickel  have  been 
found,  and  manganese  is  widespread  in  the  silver  veins, 
though  wanting  in  copper-bearing  ones.  Zinc  is  not  limited 
in  distribution,  but  is  more  abundant  in  the  silver  veins. 

The  deposition  of  the  ores  is  considered  by  Weed  to  be 
due  to  aqueous  alkaline  solutions,  which  have  probably 


286          ECONOMIC   GEOLOGY   OF   THE   UNITED   STATES 

leached  the  metals  from  the  granite  at  considerable  depths. 
These  solutions,  which  came  up  in  the  fissures,  were  hot, 
but  not  necessarily  under  pressure.  Where  the  fissures 
were  open  they  were  filled  with  ore,  and  where  narrow, 
replacement  of  the  walls  occurred,  so  that  the  vein  matter 
shades  off  into  the  country  rock.  Since  their  formation 
faulting  has  occurred,  usually  parallel  to  the  vein.  The 
entrance  of  meteoric  waters  into  the  vein  has  carried  much 
ore  downward,  resulting  in  a  richer  zone  below  even  the 
zone  of  oxidation,  and  showing  bornite,  chalcocite,  and 
covellite  as  a  result  of  this;  some  of  these  have  been 
derived  from  the  breaking  up  of  the  pyrite.  It  has  been 
found  that  these  bonanza  bodies  of  secondary  origin  pass 
downward  into  lower-grade  ores.  Most  of  the  ores  are 
put  through  a  process  of  mechanical  concentration  before 
being  sent  to  the  smelter.  The  vertical  limits  of  the  ore 
have  not  yet  been  determined,  but  certain  silver  mines 
have  reached  a  depth  of  1450  to  1500  feet,  while  most  of 
the  copper  mines  have  gone  to  2000  or  2500  feet. 

The  history  of  this  mining  camp  is  full  of  interest.  Butte  in  1864 
was  a  gold  camp,  but  difficulties  in  working  the  gravels  directed  atten- 
tion to  the  mineral-vein  outcrops,  and  unsuccessful  attempts  were  made 
to  work  their  copper  and  silver  contents,  so  that  it  was  not  until  1875, 
following  a  period  of  quiescence,  that  the  discovery  of  rich  silver  ore 
in  the  Travona  lode  revived  the  mining  industry  of  Butte.  In  1877 
several  silver  mines  were  opened,  followed  by  others ;  but  this  did  not 
last  many  years,  for  with  the  drop  in  the  price  of  silver  many  mines 
closed,  although  one,  the  Bluebird,  had  produced  2,000,000  ounces  of 
silver  from  1885  to  1892. 

The  copper  mines  were  worked  to  only  a  limited  extent  at  first, 
and  the  industry  did  not  assume  permanence  until  1879-1880,  when 
niatte  smelting  was  introduced.  In  1881  the  Anaconda  mine,  which 


COPPER  287 

was  first  worked  for  silver,  began  to  show  rich  bodies  of  copper  ore, 
and  since  then  the  output  of  copper  has  steadily  increased,  there  being 
a  number  of  large  smelting  plants  distributed  between  Butte,  Ana- 
conda, and  Great  Falls. 

Up  to  the  end  of  1896  the  commercial  value  of  the  copper  pro- 
duced was  about  $330,000,000.  This  greatly  exceeds  the  total  output 
of  Leadville,  and  nearly  equals  the  famous  Comstock  lode.  W.  H. 
Weed  has  estimated  that  up  to  January  1,  1897,  the  district  had 
yielded  500,000  ounces  of  gold,  100,000,000  ounces  of  silver,  and 
1,600,000,000  pounds  of  copper.  In  1887  Butte  passed  the  Lake  Superior 
District  in  the  production  of  copper,  and  has  kept  ahead  of  it  ever  since, 
having  in  1903  produced  38.9  per  cent  of  the  United  States  produc- 
tion. 


GEOLOGICAL  CROSS-SECTION  OF  THE  COPPER  MINING  REGION 
FIG.  55.  —  Section  across  Keweenaw  Point.    After  Rickard. 

Michigan  (2,24-26).  —  This  region,  which  was  discovered 
in  1830  by  Douglas  Houghton,  a  young  geologist,  has 
become  one  of  the  most  famous,  and  for  some  years  one 
of  the  leading,  copper-producing  districts  of  the  world. 

The  rocks  of  the  region,  known  as  the  Keweenaw  series, 
consist  of  steeply  northwesterly  dipping,  interbedded  lava 
flows,  sandstones,  and  conglomerates.  These  form  a  belt 
from  2  to  6  miles  wide,  which  extends  from  Houghton  to 
the  end  of  the  Keweenaw  peninsula,  and  rises  as  a  ridge 
from  400  to  800  feet  above  the  lake,  being  flanked  on 
either  side  by  Potsdam  sandstone  (Fig.  55). 

The  ore,  which  is  native  copper,  and  is  occasionally  asso- 
ciated with  native  silver,  occurs  (1)  as  a  cement  in  the 


288          ECONOMIC   GEOLOGY   OF   THE   UNITED   STATES 

conglomerate  of  porphyry  pebbles  or  replacing  the  latter ; 
(2)  as  a  filling  in  the  amygdules  of  the  lava  beds ;  (3)  as 
masses  of  irregular  and  often  large  size,  in  veins  with 
calcitic  and  zeolitic  gangue. 

The  veins,  which  cut  both  the  igneous  and  sedimentary 
rocks,  have  yielded  much  copper  in  former  years,  and  the 
large  masses  obtained  from  them  have  made  the  region 
famous;  but  at  the  present  time  about  75  per  cent  of  the 
production  comes  from  the  Calumet  conglomerate,  while 


FIG.  56.  —  Section  showing  occurrence  of  amygdaloidal  copper,  Quincy  mine, 
Mich.    After  Rickard,  Eng.  andMin.  Jour.,  LXXVIII:  626,  1904. 

the  balance  comes  from  two  other  copper-bearing  conglom- 
erates known  as  the  Albany  and  the  Allouez,  and  from 
the  ash-beds  and  amygdaloids,  whose  gas  cavities  are  filled 
with  a  mixture  of  native  copper,  calcite,  and  zeolites. 

A  curious  and  hitherto  unexplained  feature  is  the  irregu- 
lar distribution  of  the  copper  in  the  different  beds.  Thus 
the  Calumet  conglomerate  carries  practically  no  ore  outside 
of  the  Calumet  and  Hecla  ore  shoot  which  is  three  miles  long, 
12-15  feet  thick,  and  has  been  mined  to  a  depth  of  5000  feet. 

Various  theories  have  been  brought  forward  to  account 
for  the  origin  of  the  copper  ores  in  this  region. 


COPPER  289 

That  it  is  not  a  true  contact  deposit  is  shown  by  the  fact 
that  the  amygdules  in  the  diabase,  the  fissure  veins,  and  the 
crevices  in  the  broken  pebbles  are  filled  with  copper,  show- 
ing a  subsequent  deposition.  The  diabase  was  looked  upon 
by  Pumpelly  (25  &)  as  a  possible  source  of  the  ore,  and  since 
its  extensive  alteration  was  no  doubt  accompanied  by  the 
oxidation  of  protoxides,  this  might  account  for  the  reduc- 
tion of  copper  mineral  to  the  native  or  metallic  condition, 
it  being  known  that  ferrous  salts  may  precipitate  metallic 
copper  (1).  More  recently  Lane  (25  a)  has  suggested  that 
originally  buried  water  has  also  been  an  important  factor  in 
concentration,  but  agrees  that  the  final  precipitation  was  by 
water  working  downward.  For  the  water  in  the  upper  part 
of  the  mines  is  fresh,  below  saline,  and  copper  is  also  in  the 
iron  ores,  and  has  been  thought  to  occur  mainly  under  the 
higher  portions  of  the  point. 

Although  these  deposits  have  been  worked  in  prehistoric 
times,  as  evidenced  by  copper  implements  and  ornaments 
found  in  the  mines,  the  famous  Calumet  and  Hecla  Mine 
was  not  opened  up  until  1846.  In  1847  Michigan  pro- 
duced 213  long  tons  of  the  total  United  States  production 
of  300  tons  of  copper.  Since  1863  the  annual  output  has 
exceeded  1000  tons  and  has  gradually  and  steadily  increased, 
reaching  85,893  long  tons  in  1903,  having  a  market  value  of 
120,269,000. 

The  ores  from  this  district,  which  are  known  as  Lake  ores, 
are  all  of  low  grade,  some  running  as  low  as  .55  per  cent 
native  copper.  Owing,  however,  to  the  brittle  character  of 
the  gangue  and  the  malleability  of  the  ore,  as  well  as  their 
difference  in  specific  gravity,  it  is  possible  to  separate  the 
two  quite  thoroughly  by  crushing  in  stamps  and  concentrat- 


290          ECONOMIC   GEOLOGY   OF   THE   UNITED   STATES 

ing  by  jigs,  tables,  etc.  This  concentrated  material  is  then 
refined  by  smelting. 

Arizona  (8-16).  —  This  territory  ranks  third  as  a  producer 
of  copper  ores  in  the  United  States,  and  differs  from  most 
other  copper-producing  localities  in  supplying  chiefly  ores 
of  oxidized  character ;  in  fact,  from  1880  to  1895  Arizona  was 
the  only  copper  area  in  the  world  whose  ores  were  exclusively 
oxidized. 

The  territory  contains  four  important  districts,  all  lying 
within  the  mountain  region,  and  which  in  the  order  of  their 
importance  are,  (1)  Bisbee  or  Warren,  (3)  Jerome  or  Black 
Range,  (3)  Clifton,  Morenci,  or  Copper  Mountain,  and  (4) 
Globe.  In  all  except  the  second  the  modes  of  the  ore  occur- 
rences possess  certain  similarities. 

Bisbee  or  Warren  District. — This  district  (11,15),  which 
contains  the  famous  Copper  Queen  Mine,  lies  on  the  eastern 
slope  of  the  Mule  Pass  Mountains,  but  a  short  distance  from 
the  Mexican  boundary.  The  section  at  that  locality  involves 
strata  from  pre-Cambrian  to  Cretaceous  age,  with  an  im- 
portant unconformity  between  the  Carboniferous  and  Cre- 
taceous (Fig.  57).  Prior  to  the  deposition  of  the  latter  the 
rocks  had  been  broken  by  numerous  faults,  one  of  these,  the 
Dividend  fault,  being  specially  prominent  in  forming  one 
boundary  of  the  ore-bearing  area.  This  was  followed  by 
intrusions  of  a  granitic  magma  forming  dikes,  sills,  or 
irregular  stocks,  which  have  metamorphosed  the  Carbon- 
iferous limestones,  with  the  production  of  characteristic 
contact  minerals. 

The  ore  bodies,  which  are  generally  developed  in  the  zone 
of  metamorphic  silicates  surrounding  the  porphyry,  as  well  as 
sometimes  outside  of  it,  form  large,  irregularly  distributed, 


COPPER 


291 


but  rudely  tabular  masses,  which  are  generally  parallel  to 
the  limestone  bedding.  As  now  found  they  consist  of  oxi- 
dized ores,  such  as  malachite,  azurite,  and  cuprite,  above, 
which  pass  at  variable  depths  into  unaltered  sulphides ;  but 
between  the  two,  or  at  least  never  far  from  the  effects  of 


GENERALIZED  COLUMNAR  SECTION  OF  THE  ROCKS  OF  THE  BISBEE  QUADRANGLE. 

FIG.  57.  —  Geological  section  at  Bisbee,  Ariz.    After  Ransome.    U.  S.  Geol.  Surv., 
Prof.  Pap.  21. 

oxidation,  masses   of   massive  or  sooty  chalcocite  are  fre- 
quently found. 

The  ore-bearing  solutions  are  believed  to  have  been  stimu- 
lated by  the  porphyry  and  to  have  risen  from  an  unknown 
source,  but  although  they  may  have  followed  some  of  the 


292 


ECONOMIC   GEOLOGY   OF   THE   UNITED   STATES 


fault  fissures,  the  ore,  which  originally  consisted  of  pyrite, 
chalcopyrite,  and  occasionally  sphalerite,  owes  its  deposition 
to  metasomatic  replacement  in  the  limestone.  As  originally 
formed,  the  deposits  contained  too  little  copper  to  make 

them  of  commer- 
cial value,  but  they 
have  been  subse- 
quently enriched 
by  concentration 
due  to  weather- 
ing in  the  upper 

part'  and  second- 

ary  deposition  of 
FIG.  58.  —  Generalized  section  of  ore  bodies  at  Bisbee,  chalcocite  in  the 

underlying  zone. 

Indeed  it  is  said  that  nearly  all  the  bodies  of  workable 
sulphides  owe  their  value  to  its  presence. 

The  gossan  of  some  of  the  ore  bodies  forms  prominent 
ferruginous  ledges,  and  while  these  rarely  show  surface  in- 
dications of  copper,  still  experience  has  shown  that  they  are 
connected  with  underlying  ore  bodies;  however,  many  of 
the  latter  have  no  outcrops. 

Although  always  important,  this  region  assumed  great 
prominence  in  1903,  due  to  the  opening  and  extensive  de- 
velopment of  new  ore  bodies  of  great  extent. 

Jerome  District. — This  was  the  leading  copper-producing 
district  of  Arizona  for  1897  to  1900  inclusive,  but  then 
dropped  to  second  place.  The  mode  of  occurrence  of  the 
ore  differs  markedly  from  that  noted  in  other  areas.  It  is 
bornite  and  chalcopyrite,  which  is  associated  with  a  sheared 
dike  and  fills  fissures  and  impregnates  the  slate  rock. 


PLATE  XIX 


FIG.  1.  —  Smelter  of  Arizona  Copper  Co.,  Clifton,  Ariz.    After  Church,  Min.  Mag. 
X:  2, 1904. 


FIG.  2.  — View  of  Bingham  Cauon,  Utah.    After  Keith,    U.  S.  Geol.  Surv.,  Prof. 
Paper  38,  1905. 


COPPER  293 

Clifton  District.  —  In  this  district  (12,  13),  which  ranks 
third  among  the  Arizona  copper  districts,  the  conditions 
are  in  part  similar  to  the  Bisbee  district  in  so  far  as  the 
geologic  section  and  the  intrusion  of  porphyry  and  granite 
into  the  Palaeozoic  sediments  is  concerned.  They  have 
likewise  been  broken  by  extensive  fracturing  and  faulting, 
the  faults  sometimes  having  a  throw  of  1000  to  1500  feet, 
and  there  was  also  an  extensive  flow  of  Tertiary  eruptives. 
The  ore  bodies  differ  from  the  Bisbee  ones,  however,  in 
point  of  origin,  being  true  contact  deposits,  the  porphyry 
by  contact  influence  having  produced  great  masses  of  garnet 


FIG.  59.  —  Section  of  Morenci  district.  P,  porphyry;  S,  unaltered  sediments; 
F,  fissure  veins ;  M,  metamorphosed  limestone  and  shale ;  0,  contact  meta- 
morphic  ores ;  R,  disseminated  chalcocite.  After  Lindgren,  Eng.  and  Min. 
Jour.,  LXXVIII:  987,  1904. 

and  epidote  in  the  Carboniferous  limestones ;  and  wherever 
alteration  has  not  masked  the  phenomena,  the  metallic 
minerals,  magnetite,  pyrite,  chalcopyrite,  and  sphalerite,  are 
found  accompanying  the  contact  silicates,  and  often  inter- 
grown  with  them  in  such  a  manner  as  to  leave  no  doubt 
concerning  the  contact  origin  of  the  ores  and  the  porphyry 
as  their  source.  The  concentration  and  commercial  value 
of  the  ores  is  due,  however,  to  later  processes  intimately 
connected  with  weathering.  This  has  produced  malachite 
and  azurite  in  the  gossan,  but  some  of  the  copper  has  been 
carried  to  lower  levels  and  precipitated  as  chalcocite.  The 
sphalerite  has  been  removed  in  solution  as  zinc  sulphate,  and 
the  magnetite  and  garnet  have  yielded  silica  and  limonite. 


294         ECOKOMIC  GEOLOGY  OF  THE   UNITED   STATES 

The  ore  deposits  in  the  limestone  are  irregular  or  tabular, 
due  to  the  accumulation  of  the  minerals  along  bedding 
planes,  but  in  addition,  fissure  veins,  cutting  through  many 
of  the  rocks,  and  of  later  age  than  the  porphyry,  are  found. 

Grlobe  District  (14). — While  the  most  important  deposits 
here  occur  in  limestone,  near  the  contact  with  granite  and 
trachyte,  still  others  are  found  as  fissure  veins  in  sand- 
stone (Old  Dominion  Mine),  or  in  slate  and  gneiss,  or 
even  veinlets  in  gneiss ;  the  ores  are  largely  oxidized. 
The  output  of  this  district,  which  has  been  the  least  actively 
worked  of  any,  though  small  for  several  years,  increased 
greatly  in  1901. 

Appalachian  Region  (42,  43). — The  existence  of  copper 
in  the  Appalachian  belt  has  been  known  for  a  number  of 
years,  but  the  copper-mining  industry  has  not  been  active. 
The  early  attempts  to  work  the  deposits  were  chiefly  to 
obtain  both  gold  and  copper,  and  resulted  in  failure,  due 
chiefly  to  the  low  market  values  of  copper ;  hence  for  many 
years  the  deposits,  with  few  exceptions,  have  been  but 
little  worked,  and  it  is  only  recently  that  a  demand  for 
the  metal  and  cheaper  metallurgical  treatment  have  revived 
copper  mining. 

The  deposits  in  many  cases  occur  in  metamorphic  rocks 
scattered  over  a  wide  belt,  but  five  important  types  are 
recognizable  (42)  :  — 

1.  True  fissure  veins,  filled  with  quartz  and  copper,  the 
vein  crossing  or  conforming  to  the  banding  of  the  schists, 
and   replacement   of   the  wall  rock  being  rare.     The  ores 
are  bornite,  with  a  little  chalcopyrite  and  iron  pyrite.     The 
deposits  at  Virgilina,  Virginia,  belong  in  this  group. 

2.  True  fissure  veins  with  auriferous  quartz,  chalcopyrite, 


COPPER  295 

and  pyrite  formed  chiefly  by  replacement.  The  fissures 
are  usually  found  along  sheeting  planes,  and  the  deposits 
at  Gold  Hill,  North  Carolina,  are  taken  as  a  type  of  this 
group. 

3.  Pyrrhotite  veins  of  the  Ducktown  type  (36-38),  filling 
true  fissures,  and  consisting  chiefly  of  pyrrhotite  and  pyrite 
with   a  little   quartz.     The   ore   has  been   formed   by  the 
replacement   of   a   zone  of   sheeted   rock,  which  was  com- 
posed  chiefly   of    metamorphic   minerals,   such    as    garnet, 
actinolite,  epidote,  pyroxene,  etc.,   these   latter   being   the 
products  of  alteration  of   a  calcareous  shale.     The  Duck- 
town  ore  body  represents  a  type  forming  a  belt  extending 
all  the  way  from  Vermont  to  Alabama.     They  all  show  a 
gossan  which  can  be  mined  for  iron  ore,  while  under  this 
there  is  a  zone  of  black  copper,  the  result  of  local  enrich- 
ment,  which    passes    into   the   sulphide   ore    below.      The 
copper  is   richest   in   those   portions  where   the   pyrrhotite 
predominates.     The  Ducktown  ore,  which  has  been  worked 
for  a  number  of  years,  averages  3.5  per  cent  copper  as  it 
comes  from  the  mine.     Some  of  the  chambers  are  from  50 
to  150  feet  across,  and  from  25  to  150  feet  high  without 
timbering. 

The  great  gossan  lead  of  Virginia  and  the  copper  de- 
posits of  Ore  Knob,  North  Carolina,  also  belong  to  this 
type. 

4.  The  Catoctin  type,  representing  segregations  of  native 
copper,  copper  oxides,  and  carbonates  along  shear  zones  in 
altered  igneous  rocks  of   Algonkian  age,  the  ores  extend- 
ing below  ground  water  level.     They  are  found  at  a  num- 
ber of  localities  in  the  Appalachian  and  Piedmont  plateau 
districts,  usually  in   the  Catoctin   schist.     The  ore    shows 


296          ECONOMIC   GEOLOGY   OP   THE   UNITED   STATES 

on  the  outcrop,  but  does  not  extend  usually  more  than  50 
to  60  feet  below  the  surface.  It  is  supposed  to  have  been 
leached  out  of  the  vein  walls.  Occurrences  of  this  type 
occur  in  Green  County,  Virginia. 

5.  Deposits  of  native  copper  along  the  contact  of  diabase 
and  sandstone.  These  have  been  found  in  New  Jersey  (32,  33), 
but  are  unimportant,  although  the  mines  have  been  worked 
from  time  to  time.  Similar  occurrences  have  been  reported 
from  Pennsylvania  (34,  35)  and  Connecticut. 

Utah.  —  This  state  ranks  fourth  among  the  copper-produc- 
ing regions  of  the  United  States.  The  most  important  dis- 
trict is  that  of  Bingham  Canon  (44),  in  the  Oquirrh  range, 
southwest  of  Salt  Lake  City,  and  is  unique  in  that  it  includes 
the  oldest  mining  claim  in  the  state.  It  moreover  differs 
from  the  other  important  copper  mining  localities  in  the 
country,  in  having  a  considerable  quantity  of  gold,  silver, 
and  lead  associated  with  the  copper. 

The  rocks  of  this  district  include:  (1)  a  great  thickness 
of  sedimentaries  of  Carboniferous  age  and  divisible  into  a 
lower  member  consisting  of  massive  quartzite  with  several 
interbedded  limestones  which  carry  most  of  the  ore  bodies 
in  the  camp,  and  an  upper  member  of  quartzite  with 
black  calcareous  shales,  sandstones,  and  impure  limestones; 
(2)  igneous  rocks,  which  have  pierced  the  entire  series  of 
sedimentaries,  forming  dikes,  sills,  or  laccoliths,  and  consist- 
ing either  of  a  type  between  diorite  porphyrite  and  mon- 
zonite,  which  is  closely  associated  with  the  ore  bodies,  or  an 
andesite,  having  no  relation  to  the  ores. 

Folding,  fracturing,  and  faulting  have  greatly  complicated 
the  structural  relations  of  this  region. 

The  ores  form  lenses  in  the  limestone,  which  lie  roughly 


COPPER  297 

parallel  to  its  bedding,  or  occupy  fractures  or  fissure  zones. 
Copper,  lead,  silver,  and  gold  may  occur  in  either,  but  the 
copper  rather  favors  the  lenses,  and  the  lead  and  silver  the 
fissures. 

The  mining  operations  have  been  based  in  turn  on  the 
oxidized  gold  ores,  carbonate  ores  of  lead  and  copper,  sul- 
phides of  lead,  and  finally  sulphides  of  copper,  which  now 
constitute  the  mainstay  of  the  district.  These  copper  sul- 
phides are  cupriferous  pyrite,  chalcopyrite,  black  sulphides 
(probably  tetrahedrite),  and  chalcocite  with  a  little  galena, 
zinc,  and  siliceous  gangue.  The  pyrite,  which  is  widespread 
in  the  district,  forms  immense  replacement  bodies  in  the 
limestone,  but  is  of  secondary  importance  in  the  fissure  zones. 
The  Bingham  ores  are  of  low  value,  and  bonanzas  are  rare ; 
indeed,  the  copper  ores  can  often  only  be  profitably  worked 
because  of  their  gold,  lead,  and  silver  contents. 

California.  —  California  (17, 18,  2)  in  1903  was  fifth  in  the 
list  of  copper-producing  states,  and  owes  its  position  to  the 
output  from  Shasta  County  in  the  northern  part  of  the  state. 
This  region  lies  at  the  northern  end  of  the  Sacramento  Valley, 
and  contains  a  series  of  sedimentary  rocks,  ranging  from 
Devonian  to  Miocene  and  pierced  by  igneous  intrusions. 
Folding,  faulting,  and  shearing  are  common.  The  ore 
is  found  either:  (1)  as  sulphide  deposits  in  contact  zones, 
between  diabase  dikes  and  Carboniferous  limestones;  or  (2)  as 
bodies  of  sulphides,  in  shear  zones,  the  latter  having  been 
mineralized  with  the  development  of  irregular  ore  bodies  of 
variable  size.  The  ores  are  rare  generally  in  the  metamor- 
phosed igneous  rocks.  Superficial  alteration  has  produced 
a  gossan  wrhich  may  show  a  thickness  of  as  much  as  100  feet 
at  some  localities  (Iron  Mountain). 


298 


ECONOMIC  GEOLOGY  OF  THE  UNITED  STATES 


The  important  districts  are  the  Iron  Mountain  and  Bully 
Hill.  In  both,  the  ores  are  chalcopyrite  and  pyrite,  but 
that  from  the  latter  district  also  contains  some  bornite  and 
chalcocite.  An  analysis  of  the  Iron  Mountain  ore  gave,  Cu, 
7.45  per  cent;  S,  45.60  per  cent;  Fe,  36.97  per  cent;  Zn, 

3.41  per  cent ;  SiO2,  5.62  per  cent ; 

A12O3,  1.57  per  cent;  Moisture, 
0.88  per  cent.  This  is  probably 
higher  than  the  average  in  cop- 
per. 

Copper  deposits  are  also  known 
in  other  parts  of  California  (17). 

Other  Occurrences.  —  Colorado 
has  few  copper  mines  proper,  but 
many  of  the  ores  mined  in  the 
state  carry  copper,  and  it  is  util- 
ized by  lead  smelters  as  a  carrier 
in  the  extraction  of  other  metals. 
Copper  is  mined  in  New  Mexico 
and  Idaho,  the  Seven  Devils  Dis- 
trict of  the  latter  state  being  well 
known  (23).  The  Grand  Encampment  district  of  southern 
Wyoming  (50)  has  also  supplied  more  or  less  ore,  and  a  small 
amount  is  mined  in  Missouri  (28).  Copper  has  been  found 
at  several  localities  in  Alaska  (4-7),  but  no  shipments  were 
made  prior  to  1903. 

Uses  of  Copper.  —  Since  prehistoric  times  copper  alloyed 
with  tin  has  been  used  in  various  parts  of  the  world  for  the 
manufacture  of  bronze.  Thus  it  was  used  for  this  purpose 
in  Homeric  times,  and  it  is  found  in  the  lake  dwellings  of 


OXIDIZED  ORES 


Eleossw.  EDeNRicHED  SOLPHIOES 

FIG.  60.  —  Section  of  ore  body  at 
Bully  ffill,  Calif.    After  Diller. 


COPPER  299 

Switzerland.  The  bronze  found  in  Troy  contains  a  very  little 
tin,  and  since  this  metal  is  not  found  in  the  excavations  in 
the  West,  it  seems  probable  that  the  bronze  was  made  in 
Asia,  perhaps  in  China  or  India,  by  some  secret  process  and 
imported  to  the  western  countries. 

By  an  alloy  of  copper  and  tin,  although  both  metals 
are  soft,  a  comparatively  hard  metal  is  produced.  The 
properties  of  this  alloy,  bronze,  vary  greatly  according 
to  the  proportions  of  the  two  metallic  constituents,  and 
these  vary  with  the  use  for  which  the  alloy  is  intended. 
United  States  ordnance  is  90  per  cent  copper  and  10  per 
cent  tin,  while  ordinary  bell  metal  is  about  80  per  cent 
copper,  though  the  percentage  varies  with  the  tone  re- 
quired. Statuary  bronze  is  generally  an  alloy  of  copper, 
tin,  and  zinc ;  and,  in  these  various  bronzes,  the  color 
varies  from  copper-red  to  tin-white,  passing  through  an 
orange-yellow. 

An  alloy  of  copper  and  zinc  produces  brass,  which  is  found 
of  so  much  value  for  small  articles  used  in  building  and  for 
ornamental  purposes  in  machinery.  Copper  is  also  used  in 
roofing  and  plumbing. 

A  large  supply  of  this  metal  is  made  into  copper  wire, 
and  the  most  important  present  use  of  copper  is  in  electricity, 
for  which  its  high  conductivity  especially  fits  it  for  the 
transmission  of  electric  currents. 

Production  of  Copper. — The  production  of  copper  in  the 
United  States  has  increased  steadily  and  rapidly  in  the  last 
fifty  years,  placing  the  United  States  in  the  lead  of  the 
world's  copper  producers.  This  increase  can  be  seen  from 
the  table  given  below :  — 


300 


ECONOMIC   GEOLOGY   OF   THE   UNITED   STATES 


PRODUCTION  OF  COPPER  IN  UNITED  STATES  FROM  1845  TO  1903 


YEAR 

PRODUCTION 
LONG  TONS 

YEAR 

PRODUCTION 
LONG  TONS 

1845 

100 

1885 

74,052 

1850 

650 

1890 

115,996 

1855 

3,000 

1895 

169,917 

1860 

7,200 

1900 

270,588 

1865 

8,500 

1901 

268,782 

1870 

12,600 

1902 

294,423 

1875 

18,000 

1903 

311,627 

1880 

27,000 

PRODUCTION  OF  COPPER  IN  THE  UNITED  STATES  BY  STATES 
(In  pounds) 


SOURCE 

1901 

1902 

1903 

Arizona  

130,778,511 
33  667  456 

119,944,944 
25  038  724 

147,648,271 
17  776  756 

Colorado1  
Lake  Superior  
Montana  

9,801,783 
156,289,481 
229,870,415 

8,422,030 
170,609,228 
288,903,820 

4,158,368 
192,400,577 
272,555,854 

New  Mexico  
Utah  

9,629,884 
20,116,979 

6,614,961 
23,939,901 

7,300,832 
38,302,602 

Eastern  Atlantic  States  .  . 
All  others  

6,860,039 
4,526,341 

13,599,047 
1,935,989 

13,855,612 
3,546,645 

Of  the  several  producing  states  Montana  has  for  some 
years  been  the  first,  with  Michigan  second  and  Arizona 
third.  The  marked  decrease  of  Montana  in  1903  was  due 
to  litigation  and  labor  troubles. 


1  Including  copper  smelters  purchasing  copper  ore  and  mattes  in  the  open 
market,  sources  not  known. 


COPPER  301 

WORLD'S  PRODUCTION  OF  COPPER  IN  LONG  TONS 
COUNTRY  1903 

Chile 30,930 

Germany 21,205 

Japan 31,360 

Mexico 50,480 

Spain  and  Portugal 49,740 

United  States 311,627 

All  others 89,739 

The  total  value  of  the  imports  of  copper  (including  ore, 
matte,  and  manufactured  copper)  in  1903  was  120,441,977, 
while  the  total  value  of  the  exports  covering  the  same  class 
of  materials  was  144,365,155. 

REFERENCES  ON  COPPER 

GENERAL.  1.  Biddle,  Jour.  GeoL,  IX:  430,  1901.  (Origin.)  2.  Weed, 
Min.  Mag.,  X:185,  1904.  (United  States.)  3.  Winchell,  Geol. 
Soc.  Amer.,  Bull.  XIV: 269,  1903.  (Origin.).  — Alaska:  4.  Brooks, 
Eng.  and  Min.  Jour.,  LXXIV :  13.  (Tanana  and  Copper  River 
regions.)  5.  Mendenhall  and  Schrader,  U.  S.  Geol.  Surv.,  Bull. 
213  : 141,  1903.  (Mt.  Wrangell  region.)  6.  Rohn,  U.  S.  Geol.  Surv., 
21st  Ann.  Rept.,  II :  393,  1900.  (Chitina  River  and  Skolar  Mts.) 

7.  Schrader,  U.  S.  Geol.   Surv.,  20th   Ann.  Rept.,  VII:  341,  1900. 
(Prince    William   Sound    and    Copper    River   district.)  —  Arizona : 

8.  Blandy,  Eng.  and  Min.  Jour.,  LXIV :  97, 1897.  (Ariz.)    9.  Church, 
Amer.  Inst.  Min.  Engrs.,  Trans.   XXXIII:    3,  190-J.     (Tombstone 
district.)     10.  Douglas,  Min.  Indus.,  VI:  227,  1898.     11.   Douglas, 
Amer.  Inst.  Min.  Engrs.,  Trans.  XXIX :  511,  1900.     (Copper  Queen 
Mine).     12.  Lindgren,  U.  S.  Geol.  Surv.,  Bull.  213 : 133,  1903.    (Clif- 
ton district.)    13.  Lindgren,  Amer.  Inst.  Min.  Engrs.,  Trans.  XXXV, 
1905.     (Clifton   district.)     14.   Ransome,  U.  S.  Geol.  Surv.,  Prof. 
Paper  12,  1903.     (Globe  district.)     15.   Ransome,  U.  S.  Geol.  Surv., 
Prof .  Paper  21, 1904.    (Bisbee  district.)    16.  Wendt,  Amer.  Inst.  Min. 
Engrs.,  Trans.  XV  :  25,  1887.  —  California :  17.  Aubury,  Calif.  State 
Mining  Bureau,  Bull.  23,  1902.      18.  Diller,  Eng.  and  Min.  Jour., 
LXXIII:857,  1902.     (N.  Calif .)  —  Colorado :   19.  Emmons,   Tenth 
Census,  XIII:  68,   1885.     (Gilpin  Co.)     20.  Spencer,    U.   S.   Geol. 
Surv.,   Bull.   213:163,   1903.     (Pearl,   Colo.)     21.   Emmons,  U.  S. 
Geol.  Surv.,  Bull.   260:221,   1905.     (Red   Beds,  Colo,  plateau.)  — 


302          ECONOMIC   GEOLOGY   OF   THE   UNITED   STATES 

Georgia:  22.  Weed,  U.  S.  Geol.  Surv.,  Bull.  225:180,  1904.— 
Idaho:  23.  Lindgren,  Min.  and  Sci.  Pr.,  LXXVI1I:125,  1899. 
(Seven  Devils  district.)  —  Michigan :  24.  Irving,  U.  S.  Geol.  Surv., 
Mon.  V,  1883,  also  3d  Ann.  Kept. :  89,  1883.  25.  Lane,  Amer. 
Geol.,  XXII:  251,  1898.  (Magmatic  differentiation  in  copper 
rocks.)  25  a.  Lane,  Mich.  Miner,  Jan.-Feb.,  1904.  25  b.  Pumpelly, 
Mich.  Geol.  Surv.,  I,  pt.  2, 1873.  26.  Rickard,  Eng.  and  Min.  Jour., 
LXX VIII:  585,  625,  665,  745,  785,  865,  905,  1025,  1904.  — Missouri: 
27.  Nicholson,  Amer.  Inst.  Min.  Engrs.,  X :  444, 1882.  (St.  Genevieve 
district.)  28.  Bain  and  Ulrich,  U.  S.  Geol.  Surv.,  Bull.  260 : 233, 1905. 
(General.)— Montana:  29.  Weed,  U.  S.  Geol.  Surv.,  Bull.  213:170, 

1903.  (Butte.)     30.  Winchell,  Eng.  and  Min.  Jour.,  LXXVIII:    7, 

1904.  31.  Winchell,  Geol.  Soc.  Amer.,  Bull.  XIV: 269,  1903.— New 
Jersey :  32.  Kiimmel,  N.  J.  Geol.  Surv.,  Ann.  Kept.,  1899 : 171,  1900. 
33.  Weed,  U.  S.  Geol.  Surv.,  Bull.  225 :  187,  1904.     (Griggstown.)  — 
Pennsylvania :  34.  Bailey,  Eng.  and  Min.  Jour.,  XXXV :  88,  1883. 
(Adams  County.)     35.  Lyman,  Jour.  Franklin  Inst.,  CXLVI:416, 
1898.     (Bucks  and  Montgomery  counties.)  —  Tennessee  :   36.  Hen- 
rich,  Amer.  Inst.  Min.  Engrs.,  Trans.  XXV :  173, 1896.     (Ducktown.) 
37.    Kemp,    Amer.   Inst.   Min.   Engrs.,    Trans.    XXXI  :  244,    1902. 
(Ducktown.)     38.  Weed,  Amer.  Inst.  Min.  Engrs.,  Trans.  XXX: 
449,  1901.     (Southern  Appalachians.)  —  Texas:  39.  Schmitz,  Amer. 
Inst.   Min.    Engrs.,    Trans.    XXVI :  97,    1897.      (Permian  ores.) — 
United    States :    40.    Douglas,    Amer.    Inst.    Min.    Engrs.,    Trans. 
XIX:  678,   1891.     41.   Stevens,   Copper   Handbook,   published  an- 
nually at  Houghton,  Michigan,  by  the  author,  $5.     42.  Weed,  U.  S. 
Geol.  Surv.,  Bull.  213  : 181,  1903  (Appalachians)  ;  and  Bull.  260 : 217, 

1905.  (E.  U.  S.)     43.  Weed,  U.  S.  Geol.  Surv.,  Bull.  260  :  211,  1905. 
(U.  S.  localities  and  industry.)  —  Utah :  44.  Boutwell,  U.  S.  Geol. 
Surv.,  Bull.  213  : 105, 1903.    (Bingham.)    Also  U.  S.  Geol.  Surv.,  Prof. 
Paper  38,  1905.  —  Vermont :  45.  Weed,  U.  S.  Geol.  Surv.,  Bull.  225 : 
190,  1904.    46.   Smyth  and  Smith,  Eng.  and  Min.  Jour.,  April  28, 
1904.  —  Virginia :   47.   Watson,  Geol.  Soc.  Amer.,  Bull.  XIII:  353, 
1902.    ( Virgilin a  district.)  —  Wisconsin:  48.  Grant,  Wisconsin  Geol. 
and  Nat.  Hist.  Surv.,  Bull.  No.  6, 1900.     (Douglas  Co.)  —  Wyoming  : 
49.  Kennedy,  Eng.  and  Min.  Jour.,  LXVI:  640,  1898.     50.  Spencer, 
U.  S.  Geol.  Surv.,  Bull.  213  : 158,  1903.     (Encampment  region.) 


CHAPTER  XVI 
LEAD  AND  ZINC 

THESE  two  ores  can  hardly  be  treated  separately  for  the 
reason  that  they  occur  so  often  associated  with  each  other ; 
the  combination  of  lead  and  silver,  of  importance  in  the 
Rocky  Mountain  region,  is  treated  under  a  separate  head. 

Ores  of  Lead.  —  The  ores  of  lead,  together  with  their  com- 
position and  the  percentage  of  lead  which  they  contain,  are :  — 
Galena,  PbS,  86.4 ; 
Cerussite,  PbCO3,  77.5; 
Anglesite,  PbSO4,  68.3; 
Pyromorphite,  Pb3P2O8  +  £  PbCl2,  76.36. 
Of  these,  galena  is  the  commonest,  while  the  other  two  are 
usually  found  in  those  localities  where  superficial  oxidation 
of  the  ore  deposit  has  taken  place.     The  lead  obtained  from 
argentiferous  ore  is  commonly  spoken  of  as  desilverized  or 
hard  lead,  while  that  from  non-argentiferous  ones,  such  as 
those  of  the  Mississippi  Valley  areas,  is  known  as  soft  lead. 

Ores  of  Zinc.  —  The  ores  of  zinc,  together  with  the  per- 
centage of  zinc  they  contain,  are :  — 
Sphalerite,  ZnS,  67 ; 
Smithsonite,  ZnCO3,  51.96 ; 
Calamine,  H2Zn2SiO6,  54.2; 
Zincite,  ZnO,  80.3; 
Willemite,  Zn2SiO4,  58.5; 

Franklinite  (FeZnMn)O(FeMn)2O3,  composition  vari- 
able but  containing  about  51.8  Fe  and  7.5  Mn. 


304          ECONOMIC   GEOLOGY   OF  THE  UNITED   STATES 

Of  these  ores,  sphalerite  (also  known  as  blende,  jack,  or 
black-jack)  is  by  far  the  most  important,  except  in  northern 
New  Jersey,  where  it  is  practically  lacking  and  franklinite 
and  willemite  abound.  With  few  exceptions,  zinc  is  con- 
stantly associated  with  lead,  and  at  times,  as  in  portions  of 
the  Cordilleran  region,  carries  silver  or  even  gold. 

Calcite,  dolomite,  and  pyrite  are  common  gangue  minerals 
of  non-argentiferous  lead,  and  zinc  ores,  and  others  may 
occur  at  certain  localities.  In  the  argentiferous  ores,  quartz 
is  probably  the  commonest  gangue  mineral,  but  there  may 
be  other  less  important  ones. 

Iron,  lead,  and  manganese  are  not  uncommon  impurities 
in  zinc  ores,  and  those  of  Missouri  contain  small  amounts  of 
cadmium,  but  this  is  not  injurious,  as  it  is  more  volatile  than 
the  zinc  and  easily  driven  off  by  heat. 

Argentiferous  lead  ores  sometimes  contain  antimony, 
arsenic,  and  iron  as  impurities.  Those  of  the  Appala- 
chians, which  are  practically  non-argentiferous,  are  free  from 
most  of  these. 

Neither  lead  or  zinc  ores  are  restricted  to  any  one  forma- 
tion, but  the  majority  of  economically  valuable  deposits  of 
these  metals,  without  silver,  gold,  or  copper,  are  found  in  the 
Paleozoic  formations,  although  a  few  are  known  in  pre- 
Cambrian  rocks.  They  exist  as  disseminations,  chamber 
deposits,  as  filling  in  brecciated  zones,  in  gash  veins  and 
replacements.  While  the  metallic  contents  of  the  ore  as 
mined  is  often  low,  still,  owing  to  the  great  difference  in 
gravity  between  ore  and  gangue  (excepting  pyrite),  it  is 
often  possible  to  separate  them  by  mechanical  concentration ; 
and  for  the  zinc  ores  magnetic  separation  has  been  success- 
fully tried. 


LEAD   AND   ZINC 


305 


Superficial  Alteration  of  Lead  and  Zinc  Ores.  —  Galena  is 
often  altered  near  the  surface  to  anglesite  or  cerussite.  The 
former,  however,  is  unstable  in  the  presence  of  carbonated 
waters  and  changes  readily  to  carbonate.  Phosphates  are 
developed  in  rare  instances. 

Sphalerite,  the  common  ore  of  zinc,  is  often  changed  super- 
ficially to  smithsonite,  hydrozincite,  or  calamine.  Such  oxi- 
dized ores  are  of  greater  value  than  unoxidized  ones,  because 


FIG.  61.  —  Map  showing  distribution  of  lead  and  zinc  ores  in  United  States. 
Adapted  from  Ransome,  Min.  Mag.,  X:  1. 

although  carrying  a  lower  percentage  of  zinc,  they  occur  in 
a  more  concentrated  form  and  yield  more  easily  to  metal- 
lurgical treatment. 

Distribution  of  Lead  and  Zinc  Ores  in  the  United  States.  — 

The  occurrence  of  lead  or  zinc  with  gold,  silver,  and  copper 
is  confined  chiefly  to  the  Cordilleran  region,  and  shows  a 
most  varied  mode  of  occurrence;  but  commercially  valuable 
deposits  of  lead  alone,  or  lead  and  zinc,  are  confined  to  the 


306 


ECONOMIC   GEOLOGY   OF   THE   UNITED   STATES 


Mississippi  Valley,  while  those  of  zinc  alone  or  with  little 
lead  are  restricted  to  the  Appalachian  region  as  seen 
below. 


Lead  Alone.  Appalachian  Belt  (11,  25,  29).  — Lead  (some- 
times argentiferous)  occurs  at  a  number  of  localities  from 
Maine  to  Georgia,  filling  small  veins  in  metamorphic  rocks, 
and  the  deposits  have  at  various  times  aroused  temporary 
interest.  There  is  no  likelihood  of  their  ever  becoming  im- 
portant producers,  although  exciting  rumors  regarding  them 
are  occasionally  circulated. 

Southeastern  Missouri  (12,  18,  19). — This  area  forms  a 
subdistrict  of  the  Ozark  lead  and  zinc  region,  to  be 

mentioned  later. 
The  galena  is 
found  in  Lower 
Silurian  lime- 
stones, the  larger 
lead  deposits  oc- 
curring in  mas- 
sive  strata  near 

RS 

FIG.  62.  — Generalized  section  of  Southeastern  Missouri   the    base,    called 
lead  region.    After  Bain.  ^    Joseph  lime. 

stone,  while  others  with  a  little  zinc  are  in  the  cherty  Potosi 
limestone  near  the  summit ;  the  sandstone  layers  are  barren. 
The  ore  forms  great  impregnations,  but  cavern  or  vein  de- 
posits so  common  in  other  parts  of  Missouri  are  wanting 
in  this  region;  while  many  small  faults  occur,  the  ore  sel- 
dom favors  them.  The  origin  of  these  ores  is  treated  under 
lead  and  zinc.  The  average  ore  runs  from  6  to  8  per  cent 
galena;  when  roughly  handpicked,  10  to  12;  and  subse- 


LEAD   AND  ZINO  307 

quent  jigging  of  the  crushed  ore  brings  the  galena  contents 
up  to  60  or  70  per  cent. 

The  Missouri  lead  mines  were  worked  at  a  very  early  date 
for  making  bullets,  and  their  product  is  said  to  have  been 
used  during  the  Revolution. 

Desilverized  Lead.  —  The  important  localities  supplying 
this  type  of  lead  are  described  under  lead-silver  ores,  but 
brief  reference  may  be  made  to  them  here.  Idaho  is  the 
most  important  producer,  more  than  96  per  cent  coming 
from  the  Cceur  d'Alene  district.  In  Utah  much  is  ob- 
tained from  the  Park  City  district  of  Summit  County, 
the  Bingham  Canon  and  Cottonwood  districts  of  Salt 
Lake  County,  and  the  Tintic  district  of  Juab  County. 
Colorado's  main  supply  is  yielded  by  the  Leadville  mines 
in  Lake  County  and  the  Aspen  mines  of  Pitkin  County, 
while  smaller  amounts  are  obtained  from  Creede,  Lake 
City,  Ouray,  and  Rico.  (See  Lead-Silver  references,  also 
map,  Fig.  73.)  (28.) 

Comparatively  little  lead  is  produced  in  the  western  states, 
except  in  the  three  mentioned  above. 

As  pointed  out  by  Bain,  the  important  lead  ores  of  this 
region  are  closely  associated  with  both  igneous  and  sedi- 
mentary rocks.  At  Leadville,  Aspen,  and  Park  City  the 
sediments  are  dolomites  and  limestones,  and  at  Cceur  d'Alene 
they  are  shales  and  quartzites.  While  the  ores  seem  to  favor 
igneous  associations,  still  the  larger  bodies  are  found  where 
both  classes  of  rocks  occur. 

Zinc  Ores.  —  The  zinc-producing  regions  of  the  United 
States  are  the  eastern  and  southern  states,  the  Mississippi 
Valley,  and  the  Rocky  Mountain  region. 


308          ECONOMIC   GEOLOGY  OF  THE   UNITED   STATES 

The  ore  from  the  different  districts  varies  in  grade,  associa- 
tions and  mode  of  occurrence. 

In  tonnage  terms,  the  main  zinc-producing  districts  are 
the  Joplin,  Missouri,  Sussex  County,  New  Jersey,  and 
Colorado.  The  Joplin  ores  are  the  main  source  of  supply 
of  the  Kansas,  Missouri,  and  Illinois  smelters,  but  Colorado 
and  even  British  Columbia  ore  is  shipped  to  Kansas. 
Most  of  the  New  Jersey  ore  is  used  for  zinc  oxide,  but 
smaller  amounts  are  exported  or  used  for  spelter. 

Eastern  and  Southern  States.  —  The  localities  where  zinc 
alone  occurs  are  Sussex  County,  New  Jersey ;  Saucon  Valley, 
Pennsylvania ;  and  the  Virginia-Tennessee  belt.  Of  these 
the  first  is  the  most  important,  and  the  third  yields  a  little 
lead. 

Sussex  County,  New  Jersey  (20-22). — The  output  of  these 
mines  is  second  in  importance  to  those  of  the  Mississippi 
Valley  region.  The  district  includes  two  general  mining 
areas  situated  close  together,  the  one  called  Mine  Hill,  at 
Franklin,  and  the  other  called  Sterling  Hill,  at  Ogdens- 
burg,  two  miles  farther  south,  but  not  now  worked. 

The  ore-bearing  minerals,  which  represent  a  unique  type 
of  occurrence,  consist  of  franklinite,  zincite,  willemite,  and 
calamine,  the  typical  ore  being  a  granular  mixture  of  frank- 
linite and  calcite,  with  zincite  and  willemite  scattered 
through  it.  Manganese  minerals  are  also  present,  thus  giv- 
ing a  combination  of  three  common  elements,  viz.,  man- 
ganese, zinc,  and  iron. 

The  average  mineralogical  composition  of  the  Franklin 
Furnace  ore  (Ingalls)  is  franklinite,  51.92 ;  willemite, 
31.58  ;  calcite,  12.67  ;  zincite,  .52  ;  other  silicates,  3.31 ; 


LEAD   AND  ZINC  309 

while  the  average  chemical  composition  is  :  Fe2O3,  32.06  ; 
MnO,  11.06  ;  ZnO,  29.35;  CaCO3,  12.67;  silica  and  in- 
soluble matter,  14.57. 

The  ore  body  at  both  localities  is  interbedded  with  a 
white  crystalline  limestone  of  probably  pre-Cambrian  age, 
which  in  turn  rests  on  gneiss.  The  Ogdensburg  ore  deposit 
forms  a  great  hook,  giving  two  veins  apparently,  and  the 
ore  body  seems  to  be  an  impregnated  streak  of  limestone  ; 
while  at  Mine  Hill  the  northerly  pitching  ore  body  is  also 


FIG.  63.  —  Model  of  Franklin  zinc  ore  body.    After  Nason,  Aiuer.  Inst.  Min. 
Engrs.,  Trans.  XXIV:  127. 

a  synclinal  fold,  whose  southern  end  in  addition  appears 
to  be  doubled  over  into  an  anticline.  In  both  cases  the 
wall  rock  is  heavily  impregnated  at  the  bends  of  the  fold 
with  franklinite  and  other  minerals,  while  the  ore  bodies 
are  pierced  by  intrusive  rocks.  The  origin  of  these  de- 
posits is  of  unusual  interest,  for  they  not  only  contain  in 
abundance  a  number  of  zinc  minerals  rare  or  unknown 
elsewhere,  but  many  other  mineral  species  as  well.  No 
sulphides  of  either  zinc  or  iron  have  been  noted,  to  suggest 
a  derivation  from  that  source,  and  faults  which  might  serve 
as  ore  channels  are  likewise  lacking,  consequently  their 
origin  is  difficult  to  explain. 


310 


ECONOMIC   GEOLOGY   OF   THE   UNITED   STATES 


Kemp  (20)  considers  that  the  ore  was  probably  deposited 
from  solutions  stimulated  by  intrusions  of  granite,  and  sub- 
sequently metamorphosed,  but  Wolff  (21)  suggests  that  they 
are  contemporaneous  in  form  and  structure  with  the  in- 
closing limestones,  and  hence  older  than  the  granites.  The 
extent  to  which  they  have  been  metamorphosed  has  served 
to  hide  their  original  character,  and  theories  regarding  their 
possible  origin  have  been  largely  speculative. 


FIG.  64.  —  Section  of  Bertha  zinc  mines,  Wythe  Co.,  Va.,  showing  irregular 
surface  of  limestone  covered  by  residual  clay  bearing  ore.  After  Case,  Amer. 
Inst.  Min.  Engrs.,  Trans.  XXII:  520. 

These  ore  bodies  are  of  some  historic  interest,  having  been  prospected 
as  early  as  1640  and  mined  in  1774.  The  Mine  Hill  deposits  were  worked 
for  iron  ore  as  early  as  the  beginning  of  the  last  century,  the  zinc  mining 
having  begun  about  1840.  The  ores  are  now  treated  by  magnetic  sepa- 
rators, which  remove  the  franklinite  and  garnet  from  the  willemite  and 
zincite,  while  the  calcite  is  taken  out  by  jigging.  The  zinc  ores  are  used 
for  metallic  zinc  and  zinc  white,  and  the  manganese  for  Bessemer  steel. 

Virginia-Tennessee  Belt  (32-35,  26,  27). — Zinc  and  some 
lead  occur  in  a  belt  extending  from  southwest  Virginia 
into  Tennessee.  The  ores  are  intimately  associated  with 
Cambro-Ordovician  limestone,  and  show  two  types,  viz. : 
(1)  secondary  or  weathered  ores,  including  calamine,  smith- 


LEAD   AND   ZINC  311 

sonite,  and  cerussite,  which  are  concentrated  in  the  residual 
clays  next  to  the  irregular  weathered  surface  of  the  lime- 
stone (PL.  XVII,  Fig.  2);  and  (2)  primary  ores,  including 
sphalerite,  galena,  and  some  pyrite,  belonging  to  the  dis- 
seminated replacement  breccia  type,  and  which  have  been 
localized  by  ground  waters  along  the  crushed  and  faulted 
axes  of  the  folds.  The  gangue  minerals  are  chiefly  calcite, 
dolomite,  and  some  barite.  Fluorite  is  known,  and  quartz 
may  occur  in  the  form  of  chert.  One  deposit  only,  in  Albe- 
marle  County,  is  found  in  schist,  and  is  closely  associated 
with  igneous  rocks. 

Pennsylvania  (25  a). — The  Saucon  Valley  deposits  promised 
at  one  time  to  become  prominent  producers,  but  have  not, 
owing  more  to  geological  conditions  than  actual  scarcity  of  ore. 

Lead  and  Zinc  Ores  of  the  Mississippi  Valley  Region.— 
This  includes  two  important  areas,  viz.,  the  Upper  Missis- 
sippi Valley  and  the  Ozark  Region. 

Upper  Mississippi  Valley  Area  (36,  8,  9). — This  area  em- 
braces southwestern  Wisconsin,  eastern  Iowa,  and  north- 
western Illinois,  but  the  first-named  state  contains  the 
most  productive  territory.  The  section  in  the  Wisconsin 
area,  which  may  be  taken  as  typical,  involves  the  following 
formations,  beginning  at  the  top :  — 

Niagara  limestone Silurian. 

Cincinnati  (Maquoketa)  shales 

Galena  limestone 250  ft. 

Trenton  limestone  .  .  .*  .  40-100  ft. 
St.  Peter's  sandstone  ....  150  ft. 
Lower  magnesian  limestone,  100-250  ft. 


Ordovician. 


Potsdam  sandstone    .  700-800  "    '  Cambrian' 


ft.J 
ft./ 


312 


ECONOMIC   GEOLOGY  OF  THE   UNITED   STATES 


A  bituminous  shaly  layer,  known  as  the  oil  rock,  occurs 
at  the  base  of  the  Galena,  and  below  it,  or  at  the  top  of 
the  Trenton,  is  a  fine-grained  limestone  called  the  glass  rock. 
While  the  series  as  a  whole  shows  a  very  gentle  southwest 
dip,  there  are  a  few  low  folds. 

The  ore-bearing  minerals,  consisting  of  galena,  smith- 
sonite,  and  sphalerite,  associated  with  marcasite  and  some 


FIG.  65.  —  Section  showing  occurrence  of  lead  and  zinc  ore  in  Wisconsin,  show- 
ing fissure  ore  in  flats  and  pitches,  and  disseminated  ore  in  oil  rock.  After 
Chamberlin. 

calcite,  occur  as  disseminations,  as  honeycomb  masses  in 
brecciated  or  porous  limestone,  and  in  crevices.  The  last 
type,  which  forms  the  most  important  source  of  the  ore, 
consists  of  a  vertical  fissure,  which  at  its  lower  end  splits 
into  two  horizontal  branches  called  flats,  while  these  in 
turn  pass  into  a  steeply  dipping  fissure  termed  pitches 
(Figs.  42  and  65).  There  are  at  times  several  flats.  Galena 
commonly  predominates  in  the  crevices,  while  sphalerite 
occurs  in  great  abundance  lower  down.  The  main  crevices 
extend  approximately  east  and  west,  but  there  are  other 


LEAD   AND   ZINC  313 

less  important  intersecting  fissures.  The  Galena  limestone 
is  the  most  important  ore-bearing  formation,  but  ore  is 
also  known  to  occur  in  the  lower-lying  limestones  and 
sandstones,  although  no  deposits  have  been  worked  in 
them.  In  the  crevices  the  order  of  deposition  is  mar- 
casite,  sphalerite,  and  galena.  The  ores,  are  frequently 
oxidized,  yielding  smithsonite  and  some  calamine. 

A  careful  study  of  the  origin  of  the  ore  bodies  indicates 
that  the  metallic  minerals  have  been  gathered  by  circulat- 
ing meteoric  waters  from  the  Galena  limestone ;  these  waters 
entered  the  limestone  probably  from  the  northeast,  where 
the  overlying  shales  had  been  eroded,  and  moved  to  the 
southwest.  The  ore  was  precipitated  in  crevices  as  sul- 
phides, either  because  of  a  reducing  action  exerted  by  bitu- 
minous matter  present  in  the  rocks  or  hydrogen  sulphide. 

Surface  waters  descending  crevices  have  produced  a  sec- 
ondary concentration,  which  has  resulted  in  a  separation 
of  the  zinc  and  galena,  accompanied  by  a  transferal  of 
much  of  the  former  to  lower  levels. 

Lead  was  discovered  in  the  Upper  Mississippi  area  as  early  as  1692, 
and  the  first  mining  was  done  in  Dubuque  in  1788.  The  early  work 
was  i-estricted  to  lead  mining  entirely,  the  zinc  ores  being  disregarded. 
Owing  to  uncertainty  regarding  the  size  of  the  deposits,  the  mining  for 
many  years  has  been  done  in  a  most  primitive  manner,  but  more  re- 
cently prospecting  at  lower  levels  and  the  discovery  of  new  ore  bodies 
has  stimulated  the  erection  of  better  plants.  Mechanical  concentration 
methods  have  also  been  introduced,  and  while  the  galena  can  be  sepa- 
rated quite  thoroughly  from  the  sphalerite  and  marcasite,  the  last  two 
are  parted  with  difficulty.  On  account  of  the  presence  of  marcasite 
in  most  of  the  mines,  the  zinc  ores  of  this  district  command  a  lower 
price  than  those  from  other  areas.  For  this  same  reason  much  of  the 
ore  cannot  be  used  for  spelter,  but  is  employed  for  zinc  oxide  and  sul- 
phuric acid  manufacture. 


314  ECONOMIC    GEOLOGY   OF  THE   UNITED   STATES 


Ozark  Region  (12,13,15,17). — The  position  of  the  region 
is  shown  on  the  map,  Fig.  66.  The  southern  part  of  the 
area  is  underlain  by  Carboniferous  sandstone  and  shales, 

while  the  northern 
part,  forming  the 
Ozark  plateau,  and 
containing  the  lead 
and  zinc  deposits, 
is  underlain  by 
slightly  disturbed 
sedimentaries.  In 
the  eastern  part  of 
the  plateau,  or  Salem 
Upland,  they  are 
Cambro-Silurian  dol- 
omites and  magne- 
sian  limestone,  while 


FIG.  66.  —  Map  of  Ozark  region.    After  Branner, 
Eng.  and  Min.  Jour.,  LXXI1I:  475. 


those  of   the   western   portion,  or   Springfield  Upland,  are 
Lower  Carboniferous  limestones. 

Within    this    region    the    following    four    districts    are 
recognized :  — 

1.  Southeastern    Missouri,    yielding    lead    from    dissem- 
inated ores.     This   area  has  been   mentioned   under  Lead 
Alone. 

2.  Southwestern  Missouri,  or   the    Missouri-Kansas  dis- 
trict, with  Joplin  as  the  most  important  mining  town.     It 
yields   chiefly  zinc,   with  some   lead.     The   ore   occurs  in 
limestones   of   Subcarboniferous    age,   filling    fissures,   as   a 
cement  of  brecciated   patches,  or   more   rarely  parallel  to 
the  bedding.     The  ore  bodies  are  sometimes  hundreds  of 
feet  in  diameter.     In   some   cases  the  ore  extends  to  the 


LEAD    AND   ZINC  315 

surface,  and  is  then  usually  surrounded  by  more  or  less 
residual  clay. 

3.  Central  Missouri   district,   containing   small   deposits 
of  both  lead   and   zinc.     In   this   area   the   ore   as  far   as 
exploited     occurs 

rather  in  vertical 
crevices  or  chim- 
neys than  in  brec- 
cias. 

4.  The  nor  them 
Arkansas  district, 
but  partly  devel- 
oped,    and     with    .  unj=3  __  __      M          H          IIS          S3 

many  rich  ores,  oc- 

i      i-i    1     FIQ.  67.  —  Generalized  section  showing  occurrence  of 
lead   and   zinc  ore   in   southwest  Missouri.    After 
deposits    (dissem-      Bain- 

inations),  veins  (in  faults  or  filling  breccias),  or  as  altera- 
tions. 

The  common  ores  are  sphalerite  and  galena,  with  a  gangue 
of  secondary  chert,  dolomite,  calcite,  and  barite.  Residual 
clays  occur  in  some  mines,  and  bitumen  is  not  uncommonly 
found  with  the  ores. 

These  deposits  afford  an  interesting  example  of  the  para- 
genesis  of  minerals,  the  succession  seeming  to  be  (Win- 
slow,  Trans.  Am.  Inst.  Min.  Engrs.,  p.  651,  1893)  dolomite, 
blende,  galena,  barite,  calcite,  and  pyrite. 

The  ores  of  this  region  are  mechanically  concentrated 
after  mining,  and  the  composition  of  an  average  sample  of 
3800  carloads  of  blende  shipped  from  the  Joplin  district 
in  the  first  part  of  1904  is  given  by  Ingalls  as :  Zn,  58.26 ; 
Cd,  .304;  Pb,  .70;  Fe,  2.23;  Mn,  .01;  Cu,  .049;  CaCO3, 


316          ECONOMIC   GEOLOGY   OF   THE   UNITED   STATES 

1.88;  MgCO3,  .85;  SiO2,  3.95;  BaSO4,  .82;  S,  30.72;  total, 
99.773. 

Origin  of  the  Ores.  —  Most  of  the  theories  of  the  origin 
of  these  ores  agree  in  considering  that  their  concentration 
has  been  caused  by  circulating  meteoric  waters  which  have 
collected  the  ore  particles  from  the  limestones,  although 
in  one  instance  at  least  they  seem,  to  be  associated  with 


Fid.  68. — A  typical  hoisting  outfit  in  the  southwestern  Missouri  zinc  region. 
Photo,  by  U.  F.  Bain. 

igneous  intrusions  (19).  Analyses  of  the  limestones  show 
amounts  of  from  .001  to  .015  per  cent  of  lead  and  zinc  in  the 
Cambro-Silurian  magnesian  limestones  and  Archaean  rocks 
to  the  southeast  of  the  region,  and  from  .002  to  .003  per 
cent  in  the  Lower  Carboniferous  limestones.  These  aver- 
ages calculated  give  87  pounds  of  galena  per  acre  in  a 
one-foot  layer,  and  261  pounds  of  blende  in  the  same 
volume  of  rock.  W.  P.  Jenney,  who  studied  the  deposits 
in  some  detail,  has  emphasized  the  importance  of  ascend- 


LEAD   AND   ZINC  317 

ing  waters,  while  Winslow  has  argued  for  their  concen- 
tration by  descending  currents. 

The  more  recent  studies  of  H.  F.  Bain  indicate  that  both 
ascending  and  descending  waters  were  active,  and  that  the 
chemical  reactions  involved  were  characteristic  of  dilute 
solutions;  rich  ores,  therefore,  indicate  great  aqueous 
activity. 

The  more  important  circulations  have  occurred  in  the 
Cambro-Silurian  limestones  and  those  of  the  Mississippi 
or  Lower  Carboniferous  series,  but  the  concentration  pro- 
cess has  been  often  repeated  in  many  different  horizons 
and  at  different  depths. - 

The  chemical  changes  which  took  place  in  the  primary 
concentration  of  the  ores  were  the  oxidation  of  sulphides 
to  sulphates,  the  transportation  of  these  in  solution,  and 
their  reprecipitation  as  sulphides  in  favorable  localities. 
The  localization  of  the  ore  bodies  has  been  due  to  the  pres- 
ence of  fissures  which  permitted  the  mixing  of  the  ore-bear- 
ing solutions,  but  the  circulation  of  the  latter  has  been 
limited  in  many  instances  by  impervious  beds  of  shale,  and 
organic  matter  has  served  as  a-  reducing  agent.  All  of  the 
ores  are  found  to  be  closely  associated  with  lines  of  sub- 
terranean seepage,  and  since  the  open  character  of  the  brec- 
cias favored  circulation,  much  ore  is  found  in  them.  Where 
folding  has  occurred,  the  water  has  also  sought  the  troughs 
of  synclines  as  in  the  Lake  Superior  district. 

In  the  section  presented  in  the  Ozark  region,  the  Devono- 
Carboniferous  shales  and  the  undifferentiated  Carboniferous 
shales  afforded  impermeable  barriers  to  circulation.  The 
former,  where  not  faulted,  held  down  the  ascending  solu- 
tions; but  where  absent  or  fissured,  the  solutions  from  the 


318          ECONOMIC    GEOLOGY    OF   THE   UNITED   STATES 

underlying  Cambro-Silurian  formation  were  able  to  pass  up- 
ward into  the  Mississippian  and  impregnate  them. 

The  Cambro-Silurian  ores  were  first  concentrated  by  deep 
circulation,  and  formed  the  disseminated  ores.  Later,  when 
erosion  cut  away  the  Devono-Carboniferous  capping,  further 
concentration  took  place  by  descending  solutions,  giving  rise 
to  the  ore  bodies  in  crevices,  breccias,  and  synclines. 

Two  concentrations  have  occurred  in  the  Mississippian 
limestones. 

The  ore  bodies  are  of  two  types,  viz. :  (1)  those  containing 
sulphides  and  clean  untarnished  minerals,  the  result  of  pri- 
mary concentration;  and  (2)  those  due  to  surface  concen- 
tration, and  containing  oxidized  ones  with  red  clay.  The 
ores  pass  into  sulphides  below  the  water  level. 

Where  ascending  solutions  alone  acted,  the  ore  bodies  are 
less  rich  but  more  reliable,  however  secondary  enrichment  of 
the  deposits  has  been  marked. 

Rocky  Mountain  States  (28).  —  Although  much  ore  is 
mined  in  this  region,  its  resources  of  this  metal  are  still 
largely  undeveloped,  and  up  to  1903  most  of  the  ore  mined 
was  either  shipped  to  Kansas  smelters  or  exported.  The 
recent  construction  of  a  zinc-smelting  plant  at  Pueblo, 
Colorado,  and  the  enlargement  of  the  oxide  plant  at 
Canyon,  Colorado,  has  largely  stimulated  the  production 
of  both  that  state  and  Utah. 

The  zinc-producing  localities  of  Colorado  are  chiefly  the 
same  as  those  yielding  lead,  Leadville  being  the  largest  pro- 
ducer. According  to  Ingalls  the  zinc  shipments  average 
about  25  per  cent  Zn,  10  Pb,  2.2  Fe,  4  SiO2,  39  S,  and  10 
oz.  Ag.  Much  zinc  ore  is  also  supplied  by  the  mines  at 


LEAD   AND   ZINC  319 

Creede  (Ingalls),  where  it  is  concentrated  to  a  product 
assaying  55-59  per  cent  Zn,  3.75-6  Pb,  and  1.1-2.1  Fe, 
which  is  shipped  to  Kansas.  The  blende  carries  2-3  oz. 
Ag  per  T.  Blende  concentrates  are  also  produced  at  Mon- 
tezuma  and  Rico,  Colorado.  The  Colorado  ores  are  usually 
of  lower  grade  than  the  Joplin  ones,  and  their  complex 
nature  makes  treatment  difficult;  indeed  until  recently  zinc 
has  been  a  source  of  loss  to  the  miners  and  smelters,  those 
ores  high  in  zinc  being  either  neglected  or  thrown  out. 

In  addition  to  Colorado,  New  Mexico  produces  considerable 
ore,  the  deposits  near  Hanover  yielding  blende  and  smith- 
sonite  (28)  from  Carboniferous  limestone  near  igneous  con- 
tacts. It  was  shipped  to  Wisconsin  for  treatment.  Utah, 
Idaho,  and  Montana  will  no  doubt  also  become  important 
sources  of  supply  in  the  future. 

Uses  of  Lead  and  Zinc.  —  Both  of  these  are  important  base 
metals,  although  in  value  of  production  they  rank  below  gold, 
silver,  copper,  and  iron,  neither  do  they  come  into  competi- 
tion with  these,  for  they  lack  the  high  tenacity  of  iron  and 
steel,  the  conductivity  of  copper,  and  the  value  resulting  from 
scarcity  possessed  by  gold  and  silver.  They  are  of  value, 
however,  on  account  of  their  high  malleability  and  the 
application  of  their  compounds  for  pigments. 

Uses  of  Lead.  —  Lead  finds  numerous  uses  in  the  arts,  the 
most  important  being  for  white  lead.  Litharge,  the  oxide 
of  lead,  is  used  not  only  for  paint,  but  also  somewhat  in  the 
manufacture  of  glass,  although  red  lead  is  more  frequently 
employed  instead. 

A  further  use  of  lead  is  for  making  pipe  for  water  supply, 
sheet  lead  for  acid  chambers,  and  shot. 


320          ECONOMIC   GEOLOGY   OF   THE  UNITED   STATES 

Among  the  alloys  formed  by  lead  are  type  metal  (lead,  anti- 
mony, and  bismuth,  with  copper  or  iron),  white  metal,  organ 
pipe  composition,  and  fusible  alloys  used  in  electric  lighting. 

In  addition  to  these,  the  acetate,  carbonate,  and  other  com- 
pounds are  used  in  medicine.  In  smelting,  lead  is  used  to 
collect  the  gold  and  silver,  and  the  bulk  of  the  lead  of  com- 
merce is  obtained  as  a  by-product  in  the  smelting  of  the 
precious  metals. 

Uses  of  Zinc.  —  Metallic  zinc  is  used  for  a  variety  of 
purposes,  partly  owing  to  its  slight  alteration  in  air,  and 
secondly,  because  it  can  be  rolled  into  thin  sheets.  In  this 
condition  it  is  used  extensively  for  roofing  and  also  for  plumb- 
ing, and  as  a  coating  to  iron  this  metal  is  extensively  called 
for  in  galvanizing.  It  is  also  used  for  cyaniding  gold. 

One  of  the  most  important  applications  is  for  making 
brass,  which  is  ordinarily  composed  of  from  66  to  83  parts 
of  copper  and  27  to  34  parts  of  zinc.  The  composition 
varies,  entirely  depending  on  the  use  to  which  it  is  to  be  put, 
and,  with  the  variation  in  proportion,  the  color  becomes  more 
golden,  or  whiter,  according  as  the  percentage  of  copper 
is  increased  or  decreased.  With  an  increase  in  the  amount 
of  zinc,  the  alloy  becomes  more  fusible,  harder,  and 
more  brittle.  Brass  was  made  long  before  zinc,  as  a  metal, 
was  discovered,  and  Aristotle  says  that  the  people  by  the 
Euxine  Sea  made  their  copper  a  beautiful  whitish  color  by 
mixing  it  with  a  white  earth  found  there.  Strabo  also  tells 
us  that  the  Phrygians  made  brass  in  this  way. 

White  metal  is  an  alloy  of  zinc  and  copper  in  which  zinc 
predominates,  and  which  is  often  employed  for  making 
buttons.  Imitation  gold  is  also  made  by  alloying  zinc 
with  a  predominance  of  copper,  varying  from  77  to  85  per 


LEAD   AND   ZINC 


321 


cent  of  the  mass,  and  this  is  in  common  use  as  "  gold  foil " 
for  gilding.  Zinc  is  also  made  use  of  in  the  construction  of 
electric  batteries. 

German  silver  has  60  parts  copper,  20  zinc,  and  20  nickel. 
Its  use  is  for  mathematical  and  scientific  instruments. 

Production  of  Lead  and  Zinc. — The  production  of  lead  in 
the  United  States  from  -1825  to  1900  was  as  follows :  — 


YEAR 

SHORT  TONS 

YEAR 

SHORT  TONS 

18^5  

1  500 

1875  

59,640 

1835 

13  000 

1885 

129  412 

1845 

30000 

1895          .  . 

170000 

1855  .    .  . 

15800 

1900  

270  824 

1865  

14,700 

About  70  per  cent  of  the  lead  produced  in  the  United 
States  is  derived  from  five  districts,  viz. :  Southeastern  Mis- 
souri; Joplin,  Missouri;  Leadville,  Colorado:  Park  City, 
Utah ;  and  Cceur  d'Alene,  Idaho. 

LEAD  CONTENT  OF  ORES  SMELTED  IN  THE  UNITED  STATES 
FROM  1901  TO  1903 


1901 

1902 

1903 

Short  tons 

73,265 

Short  tons 

51,833 

Short  tons 

45,554 

Idaho  

79,654 

84,742 

99,590 

Utah 

49,870 

53914 

51,129 

5,791 

4,438 

3,303 

New  Mexico    

1,124 

741 

613 

1  873 

1269 

2237 

4,045 

599 

1,493 

California   

381 

175 

55 

Washington     

(  1,457 

538 

Oregon,  Alaska,  South  Dakota,  !• 
Texas  J 

1,029 

\ 
[  2,184 

1,765 

Missouri,    Kansas,    Wisconsin, 
Illinois,   Iowa,   Virginia, 
Kentucky     

67.172 

79,445 

86,597 

Total    

284,204 

280,797 

292,874 

322 


ECONOMIC    GEOLOGY   OF   THE   UNITED   STATES 


The  production  of  spelter  in  the  United  States  from  1873 
to  1900  was :  — 


YEAR 

SHORT  TONS 

YEAR 

SHORT  TONS 

1873  

7,343 

1890  

63,683 

1880  

23,239 

1895  

89  686 

1885 

40688 

1900 

123  886 

PRODUCTION  OF  SPELTER  FROM  1901  TO  1903  BY  STATES 


EASTERN 

ILLINOIS 

AND 

AND 

KANSAS 

MISSOURI 

COLORADO 

TOTAL 

SOUTHERN 
STATES 

INDIANA 

Short  tons 

Short  tons 

Short  tons 

Short  tons 

Short  tons 

Short  tons 

1901 

8,603 

44,896 

74,240 

13,083 

140,822  i 

1902 

12,180 

47,096 

86,564 

11,087 

156,927  2 

1903 

12,301 

47,659 

88,388 

9,994 

877 

159,219* 

World's  Production  of  Lead.  —  This  in  1902  amounted  to 
926,895  metric  tons.  Of  this  quantity  the  United  States 
produced  approximately  26  per  cent;  Spain,  19  per  cent; 
Germany,  15  per  cent;  and  Mexico,  11  per  cent.  Of  these 
countries  Spain  and  Mexico  afforded  the  greatest  surplus 
production,  and  both  Germany  and  the  United  Kingdom 
required  more  lead  than  they  mined. 

The  figures  of  world's  production  together  with  imports 
and  exports  in  metric  tons  for  1902  are  given  below :  — 

1  Including  2716  tons  dross  spelter. 

2  Including  2675  tons  dross  spelter. 
8  Including  3302  tons  dross  spelter. 


LEAD   AND   ZINC 


323 


PRODUC- 
TION 

IMPORTS 

TOTAL 

EXPORTS 

CONSUMP- 
TION 

Austria-Hungary  .     . 
Belgium    

13,543 

19,500 

18817 

8,706 
53,000 
72730 

22,249 
72,500 
91  547 

53 
50,000 
6454 

22,196 
22,500 
85,093 

Germany       .... 

140,331 

39,006 

179,337 

23,100 

156,237 

Italy 

26494 

7  563 

34057 

5650 

28,407 

Prussia     

250 

23,000 

23,250 

23,250 

177  560 

177  560 

172  480 

5,080 

United  Kingdom   .     . 
United  States    ... 

27,100 
342,160 

235,522 
65,235 

262,622 
407,395 

24,408 
129,637 

238,214 

277,758 

World's  Production  of  Zinc.  —  The  production  of  zinc  ore 
and  spelter  in  metric  tons  for  1902  is  given  below :  — 


COUNTRY 

SPELTER 

ORE 

COUNTRY 

SPELTER 

ORB 

Germany  .     .     . 

174,927 

702,504 

Austria  .     .     . 

7,960 

31,927 

United  States     . 

143,552 

500,000 

Spain      .     .     . 

5,569 

127,618 

Belgium    .     .     . 

124,780 

3,852 

Italy  .... 

485 

149,965 

United  Kingdom 

40,244 

25,462 

Sweden  .    .     . 

48,783 

France  .... 

36,282 

57,982 

Algeria  .     .     . 

33,139 

Holland     .     .     . 

20,760 

Greece    .    .     . 

18,020 

Russia  .... 

8,280 

Tunis     .     .     . 

18,400 

The  above  table  indicates  that  the  mining  districts  and 
smelting  centers  are  not  identical.  Belgium  and  Holland 
have  a  smelting  industry  greatly  in  excess  of  the  local  min- 
ing interests,  but  in  the  United  States  they  are  in  approxi- 
mate equilibrium. 

REFERENCES  ON  LEAD  AND  ZINC 

Arkansas :  1.  Adams,  U.  S.  Geol.  Surv.,  Bull.  213  :  187,  1903.  (N.  Ark.) 
2.  Adams,  U.  S.  Geol.  Surv.,  Prof.  Paper  No.  24,  1904.  3.  Branner, 
Ark.  Geol.  Surv.,  Kept,  for  1892,  V.  (N.  Ark.)  —  Colorado  :  4.  Em- 
mons,  U.  S.  Geol.  Surv.,  Mon.  XII,  1886.  (Leadville.)  5.  Ran- 
some,  U.  S.  Geol.  Surv.,  22d  Ann.  Kept,  II :  229,  1901.  (Rico  Mts.) 


324          ECONOMIC   GEOLOGY   OF   THE   UNITED   STATES 

6.  Spurr,  U.  S.  Geol.  Surv.,  Mon.  XXXI,  1898.     (Aspen.)  —  Idaho  : 

7.  Lindgren,  U.  S.  Geol.  Surv.,  20th   Ann.  Kept.,  Ill:  190,  1900. 
(Wood  River  district.)  —  Illinois :  8.  Bain,  U.  S.  Geol.  Surv.,  Bull. 
225:  202,  1904,  and  Bull.  246,  1904.  — Iowa:  9.  Leonard,  la.  Geol. 
Surv.,  VI:  10,  1897.  —  Kentucky :  10.  Ulrich  and  Smith,  U.  S.  Geol. 
Surv.,  Prof.   Paper  No.   36,  1905.  — Massachusetts:   11.   Hubbard, 
Amer.  Jour.  Sci.,  IX:  166,  1825.  —  Missouri :  12.  Bain,  U.  S.  Geol. 
Surv.,  22d  Ann.  Kept.,  II :  23,  1901.     (Ozark  region.)     13.  Bain, 
U.  S.  Geol.  Surv.,  Bull.  267,  1905.     (Mo.)     14.  Ball  and  Smith,  Mo. 
Bureau  Geol.  and  Mines,  Bull.  Vol.  I,  2d  Series,  1903.     (Central 
Mo.)     15.   Branner,  Eng.   and  Min.  Jour.,   LXXIII :  475,   1902. 
(Ozark  region.)     16.  Jenney,  Amer.  Inst.  Min.  Engrs.,  Trans.  XXII : 
171,  1894.     (Mo.)     17.  Winslow,  Mo.  Geol.  Surv.,  Vols.  VI  and  VII, 
1894.     18.  Winslow,  U.  S.  Geol.  Surv.,  Bull.  132,  1896.     (S.  E. 
Mo.)     19.  Wheeler,   Eng.  and  Min.  Jour.,  LXXVII:   517,  1904. 
(Relation  of  lead  ore  to  igneous  rock.) — New  Jersey:  20.  Kemp, 
Trans.  N.  Y.  Acad.  Sci.,  XIII:  76,  1894.     21.  Wolff,  U.  S.  Geol. 
Surv.,  Bull.  213 :  214,  1903.    22.  Nason,  Amer.  Inst.  Min.  Engrs., 
Trans.  XXIV:  121,  1894.    A  U.  S.  Geol.  Surv.  report  by  Spencer 
is   also   in   preparation.  —  New   Mexico:    23.    Blake,   Amer.    Inst. 
Min.   Engrs.,   Trans.   XXIV:   187,   1894.     (S.   W.  New  Mexico.) 
24.  Keyes,  Min.  Mag.,  XII:  109,  1905.     (Magdalena  Mts.)— New 
York :  25.  Ihlseng,  Eng.  and  Min.  Jour.,  LXXV :  630,  1903.     (El- 
lenville.)  —  Pennsylvania:  25 a.  Clerc,  U.  S.  Geol.  Surv.,  Min.  Res. 
1882,  361.  — Tennessee:  26.  Keith,  U.  S.  Geol.  Surv.,  Bull.  225:  208, 
1904.    27.  See  also  Morristown,  Maynardville,  and  Cleveland  folios, 
U.  S.  Geol.  Surv.  — United  States:  28.  Bain,  U.  S.  Geol.  Surv.,  Bull. 
260 :  251, 1905.     29.  Whitney,  Metallic  Wealth  of  U.  S.,  1854.     (Ap- 
palachians.) —  Utah :  30.  Emmons,  Amer.  Inst.  Min.  Engrs.,  Trans. 
XXXI :  658,  1902.     (Delamar  and  Hornsilver  Mines.)     31.  Tower 
and  Smith,  U.  S.  Geol.  Surv.,  19th  Ann.   Rept.,  Ill:   601,   1899. 
(Tintic.)  —  Virginia :  32.  Boyd,  Resources  of  Southwest  Virginia, 
1881.    33.  Case,  Amer.  Inst.  Min.  Engrs.,  Trans.  XXII :  511,  1894. 
34.  Payne,  Eng.  and  Min.  Jour.,  LXXVIII :  544, 1904.     35.  Watson, 
Va.  Geol.  Surv.,  Bull.  1, 1905.     ( Va.-Tenn.)  —  Wisconsin :  36.  Grant, 
Wis.  Geol.  and  Nat.  Hist.  Surv.,  Bull.  9, 1903. 


CHAPTER  XVII 


GOLD  AND  SILVER 

GOLD  and  silver  are  obtained  from  a  variety  of  ores,  in 
some  of  which  the  gold  predominates,  in  others  silver,  while 
in  still  a  third  class  these  two  metals  may  be  mixed  with  the 
baser  metals,  lead,  copper,  and  zinc.  Few  gold  ores  are 
absolutely  free  from  silver,  and  vice  versa,  so  that  a  separate 
treatment  of  the  two  is  more  or  less  difficult ;  however  some 
lead-silver  ores,  although  they  may  carry  some  gold,  are 
sufficiently  prominent  to  be  discussed  as  a  separate  type,  and 
are  described  as  such  on  a  later  page. 

Ores  of  Gold.  —  Gold  occurs  in  nature  chiefly  as  native 
gold,  mechanically  mixed  with  pyrite,  or  as  a  telluride  such 
as  calaverite  (Au,  39.5  per  cent ;  Ag,  3.1  per  cent ;  Te,  57.4 
per  cent).1 

Ores  of  Silver.  —  The  minerals  which  may  serve  as  ores 
of  silver,  together  with  the  percentage  of  silver  they  con- 
tain, are :  — 


ORES 

Ag 

S 

Ag 
(Ag2S) 
3  Ag2S,  Sb2S3 
3  Ag2S,  As,S3 
5Ag2S,  Sb2S3 
AgCl 
AgBr 
Ag(ClBr) 
9  Ag2S,  SbjSg 

100.00 
87.1 
59.9 
65.5 
68.5 
75.3 
57.4 
64.5 
75.6 

12.9 
17.8 
19.4 
16.3 

approx. 

Argentite  silver  glance   

Stephanite,  brittle  silver,  black  silver    . 

Embolite    

Polybasite  

1  Other  tellurides  are  sylvanite,  kalgoorlite,  and  krennerite. 


326  ECONOMIC    GEOLOGY    OF    THE   UNITED   STATES 

Mode  of  Occurrence.  —  Most  of  the  gold  and  silver  mined 
in  the  United  States  is  obtained  from  fissure  veins,  or  closely 
related  deposits  of  irregular  shape  (79),  in  which  the  gold 
and  silver  ores  have  been  deposited  from  solution,  either  in 
fissures,  or  other  cavities,  or  by  replacement.  Considerable 
gold  and  a  little  silver  is  obtained  from  gravel  deposits. 
Some  true  contact  deposits  are  known.  Gold  has  been  found 
to  occur  in  rare  instances  as  an  original  constituent  of  igneous 
rocks  (1,  8,  11)  and  also  metamorphic  ones  (12),  but  there  are  no 
known  deposits  of  commercial  value  belonging  to  this  type. 

The  gold  and  silver-bearing  fissure  veins  include  two 
prominent  types  (79),  viz. :  (1)  the  quartz  veins,  and  (2)  the 
propylitic  type,  in  which  the  metasomatic  alteration  of  the 
wall  rock  is  often  propylitic,  that  is,  accompanied  by  the  for- 
mation of  chlorite  and  epidote,  but  near  the  veins  of  sericite 
and  kaolin.  In  the  quartz-vein  type  silver  is  present  usu- 
ally in  but  small  quantities,  while  in  the  propylitic  type  the 
silver  often  is  an  important  constituent. 

While  the  mode  of  occurrence  of  gold  and  silver  is  quite 
variable,  the  character  of  the  wall  rock  is  equally  so,  gold 
and  silver  ores  being  found  in  either  sedimentary  or  igneous 
rocks,  and  along  the  contact  between  the  two,  showing  that 
the  kind  of  rock  exerts  little  influence,  except  perhaps  where 
replacement  has  been  active.  On  the  other  hand  the  influ- 
ence of  locality  is  much  stronger,  for  it  has  been  found  that 
many  gold  and  silver-bearing  deposits  are  closely  associated 
with  masses  of  igneous  rock,  the  most  common  of  these  being 
diorite,  monzonite,  quartz-monzonite,  granodiorite,  while  true 
granites  are  rare  as  associates.  A  second  large  class  of  vein 
systems  shows  a  close  association  with  lavas  of  recent  age, 
and  the  telluride  ores  rather  favor  these  (6). 


GOLD   AND   SILVER  327 

Weathering  and  Secondary  Enrichment.  —  The  superficial 
alteration  of  gold  ores  differs  somewhat  from  that  of  deposits 
containing  ores  of  the  other  metals.  In  quartz  veins  with 
auriferous  pyrite,  the  change  of  the  latter  to  limonite  leaves 
a  rusty  quartz  with  nuggets  or  threads  of  free  gold,  and 
leaching  may  remove  most  of  the  iron.  Some  of  the  gold 
may  also  be  leached  out  by  the  ferric  sulphate,  formed  by 
the  oxidation  of  the  pyrite,  and  carried  to  lower  levels,  where 
it  is  reprecipitated.  Whether  the  reprecipitation  of  the  gold 
is  due  to  pyrite  or  carbonaceous  matter,  is,  in  some  cases  at 
least,  an  unsettled  question  (4,  and  Ref.  on  ore  deposits). 

The  silver  sulphides  are  changed  to  sulphates  or  chlorides, 
part  of  which  at  least  are  leached  out  of  the  gossan  and 
carried  to  lower  levels,  where  they  are  reprecipitated  by  iron 
or  even  copper  sulphides. 

Classification.  —  The  gold  and  silver  ores  are  some- 
times grouped  (80)  according  to  their  associations,  as  below ; 
this  also  has  the  advantage  of  bringing  out  more  clearly 
their  metallurgical  character. 

1.  Placers  or  gravel  deposits.  These  serve  chiefly  as  a 
source  of  native  gold,  but  may  and  often  do  contain  a  little 
silver,  much  of  which  is  never  separated  from  the  ore  in 
which  it  occurs.  These  gravels  are  derived  chiefly  from 
quartz  veins  of  Mesozoic  age  in  the  Pacific  coast  region, 
and  to  a  less  extent  from  pre-Cambrian  veins  of  the  Ap- 
palachian region  and  Black  Hills  of  South  Dakota.  Some 
are  also  derived  from  veins  in  Tertiary  lavas,  but  these 
usually  contain  the  metals  in  such  a  finely  divided  con- 
dition, or  in  such  combination,  that  they  do  riot  readily 
accumulate  in  stream  channels. 


328          ECONOMIC    GEOLOGY   OF   THE   UNITED   STATES 

2.  Quartzose  or  dry  ores,  in  which  the  gold  and  some  silver 
are  found  in  a  quartz  gangue,  and  are  either  free  or  mixed 
with  sulphides,  commonly  pyrite.     They  are  of  varying  age. 
Those  of  California,  Oregon,  and  Alaska  are  Mesozoic  and 
associated  chiefly  with  quartz  inonzonite,  granodiorite,  and 
diorite.      Another  great  class  of  post-Miocene  age,  found 
chiefly  in  Colorado,  Nevada,  and  Montana,  is  associated  with 
Tertiary  lavas  and  characterized  by  bonanzas.      The  most 
productive  ones  carry  fluorite  and  normally  also  tellurides. 
In  some,  gold  may  predominate ;  in  others,  silver.     A  third 
class,  of  pre-Cambrian  age,  is  found  in  the  Atlantic  States, 
Wyoming  and  South  Dakota,  the  last  mentioned  including 
the  famous  Homestake  Mine.     These  are  classified  as  dry 
ores,  because  they  are  not  as  a  rule  smelting  ones ;  they  con- 
tain limited  quantities  of  copper  and  lead,  but  may  have 
some  pyrite. 

3.  Gold  and  silver  bearing  copper  ores.    These  are  widely 
distributed  throughout  the  United  States,  and  exhibit  great 
differences  in  form  and  age,  neither  do  all  the  occurrences 
yield  much  gold  or  silver.     The  output  is  obtained  chiefly 
from  Colorado,  Utah,  and  Montana.     Those  of  the  last  two 
states,  which  supply  most  of  the  production,  are  found  as 
replacement  veins  in  granites  or  early  Tertiary  igneous  rocks. 
The  large  copper  deposits  of  Arizona  produce  but  little  gold 
or  silver,  with  the  exception  of  those  at  Jerome.     This  class 
of  ores  yields  about  one  third  of  all  the  silver  mined  in 
the  United  States. 

4.  Gold  and  silver  bearing  lead  ores.     This  class  includes 
a  variety  of  deposits,  containing  much  lead,  and  also  silver, 
with   gold  usually  in   subordinate   amounts.      They  occur 
chiefly  in  Colorado,  Utah,  and  Idaho,  and  furnish  about  one 


GOLD   AND   SILVER  329 

half  of  the  silver  obtained  in  the  United  States.     They  are 
discussed  separately  under  the  head  of  Silver-Lead  ores. 

A  subtype  of  this  class  is  represented  by  the  veins  of 
argentiferous  galena  and  tetrahedrite  of  the  Wood  River 
district,  Idaho.  These  are  veins  in  slates  near  the  contact 
of  intrusive  granite  and  are  of  late  Mesozoic  age.  Arizona, 
California,  Washington,  and  New  Mexico  produce  small 
amounts  of  argentiferous  lead  ores. 

Geological  Distribution.  —  Gold  and  silver  ores  have  been 
formed  at  a  number  of  different  periods  in  the  geological 
history  of  the  continent,  notably  in  the  pre-Cambrian,  Cam- 
brian, Cretaceous,  and  Tertiary  ages,  but  Silurian,  Devonian, 
and  Carboniferous  gold  deposits  are  not  definitely  known  to 
exist  in  North  America,  although  some  of  the  Appalachian 
veins  may  be  of  this  age  (79).  Silver  ores  show  much  the 
same  geological  distribution. 

Extraction.  —  Since  gold  and  silver  ores  vary  so  in  their 
mineralogical  associations  and  richness,  the  metallurgical 
processes  involved  in  their  extraction  are  varied  and  often 
complex. 

Those  ores  whose  precious  metal  contents  can  be  readily 
extracted  after  crushing,  by  amalgamation  with  quicksilver, 
are  termed  free-milling  ores.  This  includes  the  ores  which 
carry  native  gold  or  silver,  and  often  represent  the  oxidized 
portions  of  ore  bodies.  Others,  containing  the  gold  as  tel- 
luride  or  containing  sulphides  of  the  metals,  are  known  as 
refractory  ores  and  require  more  complex  treatment.  These, 
after  mining,  are  sent  direct  to  the  smelter  if  sufficiently 
rich,  but  if  not  they  are  often  crushed  and  mechanically 
concentrated.  The  smelting  process  is  also  used  for  mixed 


330          ECONOMIC   GEOLOGY   OF   THE  UNITED   STATES 

ores,  the  latter  being  often  smelted  primarily  for  their  lead 
or  copper  contents,  from  which  the  gold  or  silver  is  then 
separated.  While  in  some  cases  there  are  smelters  at  the 
mines,  still  there  is  a  growing  tendency  towards  the  central- 
ization of  the  industry,  and  large  smelters  are  now  located 
at  Denver,  Salt  Lake  City,  etc.,  which  draw  their  ore  supply 
from  many  mining  districts. 

Low-grade  ores  may  first  be  roasted,  and  the  gold  then 
extracted  by  leaching  with  cyanide  or  chlorine  solutions. 
The  introduction  of  the  cyanide  and  chlorination  processes, 
which  are  applied  chiefly  to  gold  ores,  has  permitted  the 
working  of  many  deposits  formerly  looked  upon  as  worth- 
less, and  in  some  regions  even  the  mine  dumps  are  now 
being  worked  over  for  their  gold  contents.  It  is  estimated 
that  in  1902  $8,000,000  worth  of  gold  ores  were  cyanided. 
The  chief  fields  are  in  the  Cripple  Creek  region  of  Colo- 
rado ;  the  De  Lamar  district,  Idaho ;  Marysville,  Montana ; 
Bodie,  California ;  and  in  Arizona. 

The  most  important  gold-milling  centers  of  the  United 
States  are  the  Mother  Lode  district  of  California,  the  Black 
Hills,  South  Dakota,  and  Douglas  Island,  Alaska. 

The  value  of  ore  and  bullion  is  determined  from  a  sample 
assay,  and  the  smelter,  in  paying  the  miner  for  his  ore, 
allows  for  gold  in  excess  of  $1  per  ton  of  ore  at  the  coin- 
ing rate  of  $20.67  per  ounce,  and  for  silver  at  New  York 
market  price,  deducting  5  per  cent  in  each  case  for  smelter 
losses.  Lead  and  copper  are  paid  for  in  the  same  manner, 
as  are  also  iron  and  manganese,  if  there  is  a  sufficient  quan- 
tity present.  No  allowance  is,  however,  made  for  zinc, 
and,  in  fact,  a  deduction  is  made  if  it  exceeds  a  certain 
per  cent. 


GOLD  AND   SILVER 


331 


Distribution  of  Gold  and  Silver  Ores.  —  Gold  ores  are 
widely  distributed  in  the  Cordilleran  region  and  Appa- 
lachian province,  while  the  silver  ores  are  found  chiefly 
between  the  Great  Plains  and  Pacific  coast  ranges,  exclu- 
sive of  the  Colorado  plateau  region.  This  occurrence  in 
two  widely  separated  areas  is  brought  out  in  an  interest- 
ing manner  in  Fig.  69. 


FIG.  69.  —  Map  showing  distribution  of  gold  and  silver  ores  in  United  States. 
Adapted  from  Ransome,  Min.  Mag.,  X'.  1. 

More  than  a  third  of  the  United  States  production  of 
gold  comes  from  the  southern  half  of  the  Rocky  Moun- 
tains, Colorado  being  the  main  producer.  In  this  area, 
however,  the  ores  vary  widely  in  their  mineralogical  asso- 
ciations, the  gold  occurring  mostly  in  combination  with 
silver,  lead,  copper,  and  zinc  ores,  but  also  at  times  free, 
or,  in  the  most  productive  district,  as  a  telluride. 

The  Pacific  belt,  excluding  Alaska,  supplies  about  one 
fourth  the  total  amount  of  gold  produced,  the  famous 
Mother  Lode  region,  mentioned  later,  being  the  most  im- 


332          ECONOMIC    GEOLOGY    OF   THE   UNITED   STATES 

portant  producer.  Alaska  yields  about  10  per  cent,  and 
the  Basin  Range  province  about  14  per  cent,  collected 
from  widely  separated  deposits  in  Utah,  Nevada,  Arizona, 
and  New  Mexico,  and  in  which  the  gold  is  associated  with 
copper,  silver,  or  lead. 

Probably  two  thirds  of  the  silver  obtained  in  the  United 
States  comes  from  the  Rocky  Mountain  region,  Colorado 
alone  yielding  about  one  third,  while  Montana  supplies 
about  one  third  of  the  total  amount  produced,  and  about 
three  fourths  of  this  is  obtained  as  a  by-product  in  copper 
smelting.  The  Basin  Range  province  furnishes  about  28 
per  cent,  two  thirds  of  this  coming  from  Utah,  especially 
from  the  Park  City  mines  near  Salt  Lake  City  (83). 

The  gold  and  silver  occurrences  of  the  United  States 
and  Alaska  can  be  grouped  under  five  areas,  as  follows :  — 

1.  Cordilleran  region. 

2.  Black  Hills,  South  Dakota  region. 

3.  Michigan  region. 

4.  The  eastern  crystalline  belt. 

5.  Alaska. 

Of  these,  the  first,  second,  and  fifth  are  the  most  impor- 
tant, while  the  third  is  insignificant. 

CORDILLERAN  REGION 

This  area  contains  a  number  of  important  deposits  of  gold 
and  silver  ores,  occurring  chiefly  in  quartz  veins,  and  to  a 
lesser  extent  in  gravels.  There  are  also  some  representa- 
tives of  the  propylitic  type. 

Pacific  Coast  Cretaceous  Gold-quartz  Ores.  —  Extending 
along  the  Pacific  coast  from  Lower  California  up  to  the 


PLATE  XX 


FIG.  1.  —  Kennedy  mine  on  the  Mother  Lode  near  Jackson,  Calif. 


FIG.  2.  —  Auriferous  quartz  veins  in  Maryland  mine,  Nevada  City,  Calif. 
Lindgren,  U.  S.  Geol.  Surv.,  llth  Ann.  Kept.,  III. 


After 


GOLD   AND   SILVER  333 

British  Columbia  boundary  there  is  a  gold  belt  of  great 
importance,  which  throughout  its  extent  is  characterized 
by  quartzose  ores  and  gold-bearing  sulphides.  The  de- 
posits belonging  to  this  are  especially  important  in  Cali- 
fornia, but  farther  north,  in  Oregon  and  Idaho,  the  veins 
in  many  cases  have  been  covered  up  by  the  lava  flows 
of  the  Cascade  Range,  and  those  known  in  that  region 
differ  somewhat  from  the  California  deposits  in  containing 
many  mixed  silver-gold  ores  and  also  veins  carrying  aurif- 
erous sulphides  without  free  gold.  The  ores  of  this  belt 
are  all  of  undoubted  Mesozoic  age,  and  are  accompanied 
by  many  extensive  placer  deposits,  which  have  been  derived 
by  the  weathering  down  of  the  upper  parts  of  the  quartz 
veins,  the  portions  now  remaining  in  the  ground  repre- 
senting probably  but  the  stump  of  originally  extensive 
fissure  veins  (79). 

Among  the  deposits  of  this  belt  two  groups  stand  out 
in  some  prominence,  namely,  those  of  the  so-called  Mother 
Lode  district  and  of  Nevada  County. 

Mother  Lode  Belt  (25,  27).  —  This  includes  a  great  series  of 
quartz  veins,  beginning  in  Mariposa  County  and  extending 
northward  for  a  distance  of  112  miles.  The  veins  of  this 
system  break  through  black,  steeply  dipping  slates  and 
altered  volcanic  rocks  of  Carboniferous  and  Jurassic  age,  and 
since  they  are  often  found  at  a  considerable  distance  from 
the  granitic  rocks  of  the  Sierra  Nevada,  they  have  apparently 
no  genetic  relation  with  them.  The  veins,  which  occur  either 
in  the  slate  itself  or  at  its  contact  with  diabase  dikes,  show  a 
remarkable  extent  and  uniformity,  due  to  the  fact  that  in 
the  tilted  layers  of  the  slates  there  lay  planes  of  weakness 
for  the  mineral-bearing  solution  to  follow.  The  ore  is  native 


334 


ECONOMIC   GEOLOGY   OF   THE   UNITED   STATES 


gold  or  auriferous  pyrite  in  a  gangue  of  quartz,  and  the 
average  value  may  be  said  to  vary  from  $3  or  $4  up  to  $50 
or  $60  per  ton.  The  veins  often  split  and  some  of  the  mines 
have  reached  a  depth  of  several  thousand  feet. 


FIG.  70.  —  Map  and  section  of  portion  of  Mother  Lode  district,  Calif.  Pffv,  river 
gravels,  usually  auriferous ;  Ng,  auriferous  river  gravels.  Sedimentary 
rocks:  Jm,  mariposa  formation  (clay,  slate,  sandstone,  and  conglomerate); 
Cc,  calaveras  formation  (slaty  mica  schists).  Igneous  rocks:  Nl,  latite; 
Nat,  andesite  tuffs,  breccia,  and  conglomerate;  nidi,  meta-diorite ;  Sp,  ser- 
pentine; ma,  meta-andesite ;  ams,  amphibole  schist.  From  U.  S.  Geol. 
Surv.,  Atlas  Folio,  Mother  Lode  sheet. 

Nevada  County  (26).  —  In  Nevada  County  the  mines  of 
Grass  Valley  and  Nevada  City  are  likewise  quartz  veins,  but 
they  occur  along  the  contact  between  a  granodiorite  and 
diabase  porphyry,  as  well  as  cutting  across  the  igneous  rock 
(Fig.  71).  Two  systems  of  fault  fissures  occur,  and  in 
these  the  ore  is  found  either  in  native  form  or  associated 


GOLD   AND    SILVER 


335 


with  metallic  sulphides.  The  width  of  the  vein  averages 
from  2  to  3  feet,  and  the  lode  ore  generally  occurs  in  well- 
defined  bodies  or  pay  shutes.  The  vein  filling  was  deposited 
by  hot  solution,  and  while  the  wall  rocks  contain  the  rare 
metals  in  a  disseminated  condition,  Lindgren  (26)  believes 
that  the  ores  have  been  leached  out  of  the  rocks  at  a  con- 
siderable depth.  The  mines  at  Nevada  City  and  Grass 
Valley  have  been  large  producers  of  gold  and  some  silver. 
Placer  mines  have  furnished  a  small  portion  of  the  product, 
but  at  the  present  day  these  latter  are  of  little  importance. 


\  GRANODIORITE 

'     O.MERRIFIELC 


/EIN   6.  URAL  VEIN  C.  SLATE  VEIN 


FIG.  71.  —  Section  illustrating  relations  of  auriferous  quartz  veins  at  Nevada  City, 
Calif.    After  Lindgren,  U.  S.  Geol.  Surv.,  YIth  Ann.  Sept.,  II. 

In  Oregon,  the  quartz  veins  are  worked  in  Baker  County, 
which  is  the  most  important  gold-producing  region  of  the 
state  (72,  73).  Gold  ores  with  sulphides  in  quartz  gangue 
are  worked  in  the  Monte  Cristo  district  of  Washington  (88). 

Central  Belt  of  Gold-Silver  Ores.  —  To  the  east  of  the  Creta- 
ceous gold-quartz  belt  there  lies  a  second  one,  in  the  central 
and  eastern  part  of  the  Cordilleran  region,  containing  many 
gold  and  silver  deposits  of  late  Cretaceous  or  early  Ter- 
tiary age,  although  they  occur  in  older  rocks,  such  as  Car- 
boniferous. 


336          ECONOMIC   GEOLOGY   OF   THE   UNITED   STATES 

Mercur,  Utah.  —  The  gold-silver  mines  of  the  Mercur  (85) 
district  in  Utah  form  perhaps  the  most  important  occurrence 
in  this  central  zone.  Here  the  Carboniferous  limestones, 
shales,  and  sandstones,  representing  about  12,000  feet  of 
sediments,  are  folded  into  a  low  anticline.  Near  the  center 
of  the  section  is  the  great  blue  limestone,  carrying  an  upper 
and  a  lower  shale  bed.  Quartz  porphyry  has  intruded  the 
limestone,  and  at  two  places  especially,  spread  out  laterally 
in  the  form  of  sheets,  on  whose  under  side  the  ore  is  found, 
the  silver  ores  under  the  lower  sheet,  the  gold  ores  under  the 


GREAT  BLUE  LIMESTCM 


LOWER  INTERCALATED  SERIES 
OWER   LIMESTONE 


Fio.  72.  — Section  of  Mercur,  Utah.    After  Spurr,  U.  S.  Geol.  Surv.,  16th  Ann. 
Rept.,  II. 

upper  one,  about  100  feet  above  the  first.  The  silver  ore  is 
cerargyrite  and  argentiferous  stibnite  in  a  silicified  belt  of  the 
limestone.  The  gold  is  native  and  occurs  in  a  belt  of  re- 
sidual contact  clay,  near  northeast  fissures  cutting  the  lime- 
stone, being  oxidized  in  places  and  accompanied  by  sulphides 
in  others.  The  ore  runs  1-19  ounces  of  silver  per  ton,  and 
2-3  ounces  of  gold,  with  a  gangue  of  quartz,  barite,  limonite, 
and  arsenical  sulphides.  The  silver  minerals  are  thought  to 
have  been  deposited  by  heated  solutions  which  came  up  along 
the  igneous  sheet  some  time  after  its  intrusion,  and  the  deposi- 
tion of  the  gold  ore  is  believed  to  have  taken  place  some  time 


GOLD    AND    SILVER  337 

after  the  silver  was  deposited.  Some  doubt  exists  as  to  the 
exact  source  of  the  ascending  waters,  but  in  all  probability 
they  were  derived  from  some  deep-seated  cooling  laccolith. 
The  ores  are  especially  suited  to  the  cyanide  treatment. 

Other  Occurrences.  —  The  northward  continuation  of  this 
belt  of  gold-bearing  veins  in  Idaho  and  Montana  presents 
somewhat  different  types  of  deposits,  for  there  the  veins  are 
causally  connected  with  great  batholiths  of  Mesozoic  gran- 
ite ;  and  while  the  veins  resemble  those  of  the  Pacific  Coast 
in  the  quartz  filling  and  free  gold  contents,  they  differ  from 
the  latter  in  containing  more  silver,  and  often  large  quanti- 
ties of  sulphides  with  little  free  gold.  In  fact  in  their  geo- 
logic relations  they  are  intermediate  between  the  quartz  vein 
and  propylitic  type.  Of  special  prominence  are  those  of 
Marysville,  Montana,  and  Idaho  Basin,  Florence,  etc.,  in 
Idaho.  This  difference  is  more  marked  in  the  Montana 
occurrences,  in  which  the  gold  becomes  subordinate  and  is 
obtained  as  a  by-product  in  silver  mining. 

Eastern  Belt  of  Tertiary  Gold-Silver  Veins.  —  Of  greater 
importance  than  the  preceding  class  are  the  veins  of  Tertiary, 
mostly  post-Miocene,  age,  which,  according  to  Lindgren,  are 
characteristic  of  regions  of  intense  volcanic  activity,  and  cut 
across  andesite  flows,  or  more  rarely  rhyolite  and  basalt. 
The  veins  may  be  entirely  within  the  volcanic  rocks,  or  the 
fissures  may  continue  downward  into  the  underlying  rocks, 
which  have  been  covered  by  the  extrusive  masses.  Most 
of  these  Tertiary  deposits  belong  to  the  propylitic  class, 
showing  characteristic  alterations  of  the  wall  rock.  The 
ores  are  commonly  quartzose,  and  though  either  gold  or 
silver  may  predominate,  the  quantities  of  the  two  metals  are 


338 


ECONOMIC    GEOLOGY   OF   THE   UNITED   STATES 


apt  to  be  equal.  Bonanzas  are  of  common  occurrence,  and 
on  this  account  the  mines  may  be  very  rich  but  short-lived ; 
still,  the  workable  ore  in  many,  extends  to  great  depths, 
but  is  less  rich  than  nearer  the  surface.  Extensive  and 
rich  placers  are  rarely  found  in  the  Tertiary  belt  of  veins, 
for  the  reason  that  the  fine  distribution  of  the  gold  is 
not  favorable  to  its  concentration  and  retention  in  stream 


FIG.  73.  —  Map  of  Colorado  showing  location  of  mining  regions.    After  Richard, 
Amer.  Inst.  Min.  Eng.,  Trans.,  19(M. 

channels.  Deposits  of  this  type  are  worked  in  a  number 
of  states,  including  Colorado,  Nevada,  Arizona,  New  Mexico, 
and  Idaho.  Colorado  leads  in  the  production  of  gold 
ores,  for  in  no  state  are  the  Tertiary  deposits  of  the  pro- 
pylitic  type  developed  on  such  a  scale. 

Cripple   Creek  (39,  45,  47).  —  This  district,  which  is  the 
most  important  in  this  belt,  is  a  producer  of  ores  containing 


GOLD   AND   SILVER 


339 


gold  almost  exclusively,  and  may  therefore  be  mentioned 
in  some  detail.  The  region  lies  about  ten  miles  west  of 
Pikes  Peak  proper,  but  in  the  foothills  of  this  mountain 
mass. 

The  most  common  rock  of  the  region  is  the  red  Archaean 
granite  of  Pikes  Peak,  in  which,  however,  are  inclusions  of 
still  older  schists.  In  Tertiary 
times,  the  region  was  one  of 
great  volcanic  activity,  which 
began  with  the  expulsion  of  the 
breccias  of  phonolitic  and  pos- 
sibly in  part  andesitic  types, 
and  was  followed  by  a  series  of 
phonolitic  rocks,  which  grade 
into  each  other.  Finally,  there 
were  intrusions  of  basaltic  dikes 
of  several  types. 

The  ore  is  chiefly  calaverite, 
and  to  a  less  extent  sylvanite, 
and  probably  some  other  gold- 
silver-lead  tellurides.  The  tel- 
lurides  are  often  associated 
with  auriferous  and  highly 
argentiferous  tetrahedrite,  molybdenite,  and  even  stibnite. 
Pyrite,  though  widely  disseminated  in  both  country  rock 
and  fissures,  rarely  carries  enough  gold  to  serve  as  an  ore. 
Native  gold  exists  only  as  an  oxidation  product  of  the  tel- 
luride.  The  common  gangue  minerals  are  quartz,  fluorite, 
and  dolomite ;  secondary  orthoclase  is  sometimes  prom- 
inent in  the  granites,  while  other  minerals  occur  in  small 
amounts. 


ORE  ALONG  SHEETED  ZONE'- 

FIG.  74.  —  Section  of  vein  at  Cripple 
Creek,  Colo.    After  Rickard. 


340          ECONOMIC    GEOLOGY   OF   THE   UNITED    STATES 

Two  types  of  ore  bodies  exist :  1.  Fissure  veins,  some- 
times simple,  but  more  often  compound,  and  formed  in  the 
more  or  less  closely  spaced  fractures  of  a  sheeted  zone. 
These  may  occur  in  any  kind  of  rock,  but  favor  the  brec- 
cias. Their  dip  is  generally  steep,  and  the  lode  may  vary 
from  1  foot  to  50  or  60  feet  in  width.  A  subtype  of  this 
are  composite  veins  in  sheeted  basalt  dikes. 

2.  Irregular  deposits,  often  of  large  size,  formed  by  the 
replacement  of  granite,  and  usually  occurring  close  to  or 
within  1000  feet  of  its  contact  with  the  breccias.  The 
ore  is  of  somewhat  lower  grade  than  that  found  in  the 
fissures. 

The  two  types  are  not  always  distinct,  and  in  both  the 
ore  has  been  deposited  in  relatively  small  spaces,  with  but 
small  quantities  of  gangue  minerals,  so  that  the  fissures  are 
never  completely  filled.  The  ores  which  show  oxidation 
to  a  depth  of  from  200  to  400  feet  often  occur  in  shutes, 
but  no  evidence  of  secondary  enrichment  has  been  found 
by  recent  investigators.  The  principal  productive  zone  does 
not  seem  to  extend  more  than  1000  feet  from  the  surface, 
and  while  ore  may  be  looked  for  below  this,  the  quantity 
of  it  will  probably  be  less. 

The  Cripple  Creek  ores  as  a  rule  run  low  in  silver  and 
from  1  to  10  ounces  of  gold  per  ton,  with  an  average  value 
of  $30  to  $40  per  ton.  Most  of  the  ores  are  treated  by  the 
chlorination  or  cyanide  process,  especially  the  former,  and 
about  one  sixth  of  the  output  is  shipped  directly  to  the 
smelters  at  Denver  and  Pueblo. 

The  rapid  rise  of  this  district  is  well  shown  by  the  fol- 
lowing figures  of  production.  A  maximum  was  reached  in 
1900,  since  which  the  output  has  gradually  declined. 


PLATE  XXI 


FIG.  1.  —  View  of  Independence  Mine  and  Battle  Mountain,  Cripple  Creek,  Colo. 
A.  J.  Harlan,  photo. 


FIG.  2.  —  General  view  of  region  around  Tonopah,  Nev.    ./.  E.  Spurr,  photo. 


GOLD   AND   SILVER  341 

PRODUCTION  IN  CRIPPLE  CREEK  DISTRICT  IN  1893-1903 


YEAR 

VALUE 

YEAR 

VALUE 

1893 

12010367 

1899 

f  15  658  254 

1894  

2,908,702 

1900  ...... 

18,073,539 

1895 

6  879  137 

1901 

17  261  579 

1896  

7,512,911 

1902  

16,912,783 

1897  

10,139,708 

1903  

12,967,338 

1898  

13,507,244 

Total  .... 

$123,831,562 

San  Juan  Region.  —  As  an  example  of  a  more  mixed 
type  of  ore  of  this  class  may  be  mentioned  the  San  Juan 
region  of  southwestern  Colorado,  which  includes  the  counties 
of  San  Juan,  Dolores,  La  Plata,  Hinsdale,  and  Ouray,  and  is 
one  of  the  most  important  gold  and  silver  producing  regions 
of  the  state,  being  noted  for  its  persistent  vertical  veins, 
carrying  gold,  silver,  and  lead  ores  in  varying  proportions. 
Those  in  the  vicinity  of  Rico  are  mentioned  under  Silver- 
Lead.  Other  important  mining  camps  are  Silverton,  Creede, 
Telluride,  and  Ouray. 

The  rocks  of  the  San  Juan  district  consist  of  a  series  of 
older  sedimentaries,  ranging  from  Algonkian  to  Cretaceous, 
buried  under  a  complex  of  Tertiary  volcanics,  of  both  acid 
and  basic  types.  In  the  Silverton  quadrangle  (43),  for  ex- 
ample, this  volcanic  series  is  several  thousand  feet  thick  and 
consists  of  tuffs,  agglomerates,  and  lava  flows.  The  more 
or  less  distinctly  horizontal  surface  volcanics  have  been  pen- 
etrated by  later  stocks  of  igneous  rock,  ranging  from  gabbro 
nearly  to  granite  in  composition,  and  by  many  small  dikes 
of  different  types. 

The  ore  deposits  form  lodes,  stocks,  or  masses  (locally 
called  chimneys),  and  replacement  deposits.  The  lode 


342 


ECONOMIC   GEOLOGY   OF  THE   UNITED   STATES 


fissures,  which  form  the  most  important  class,  have  been 
formed  at  several  different  periods  and  show  varying  strikes, 
but  are  often  of  great  length,  two  or  three  miles  being  not 
uncommon,  while  some  of  the  fractures  probably  extend 
continuously  for  as  much  as  six  miles.  The  ore-bearing 

minerals  are  pyrite 
and  sulphides  of  cop- 
per, silver,  lead,  or 
zinc,  in  a  gangue  of 
quartz,  barite,  calcite, 
dolomite,  rhodochro- 
site,  etc.  They  have 
probably  been  depos- 
ited from  aqueous 
solutions  either  in 
spaces  or  pores  of 
the  rock,  or  by  re- 
placement. The  ores 
are  mostly  low  grade, 
and  require  careful 
milling  to  yield  profit- 
able returns,  but  some 
are  sufficiently  rich  to  be  shipped  directly  to  the  smelter. 

Another  remarkable  development  of  veins  is  found  around 
Telluride  (42)  (Fig.  75),  one  of  which,  the  Smuggler  vein, 
has  been  traced  four  miles,  and  cuts  the  Tertiary  volcanics. 
The  ores  are  gold  and  silver  in  a  gangue  of  quartz,  with 
some  rhodochrosite,  siderite,  calcite,  and  barite.  The  ore 
bodies  around  Ouray  (36)  differ  from  those  around  Silver- 
ton  and  Telluride  in  being  found  in  the  sedimentaries  of 
the  region,  and  form  either  fissure  veins  or  replacements 


FIG.  75.  — Geologic  map  of  Telluride  district, 
Colorado,  showing  outcrop  of  more  important 
veins.  After  Winslow,  Amer.  Inst.  Min, 
Eng.,  Trans.  XXIX:  290. 


GOLD    AND   SILVER 


343 


in  quartzite  or  limestone  connected  with  vertical  fissures. 
Owing  to  the  different  degrees  of  replaceability  shown  by 
the  wall  rocks,  the  ore  bodies  present  a  most  varied  form. 
Tonopah,  Nevada.  —  Some  fine  examples  of  replacement 
deposits  are  also  known  in  Nevada,  an  excellent  one  being 
that  found  in  the  recently  discovered  mining  district  of 
Tonopah,  Nevada  (63),  which,  although  opened  up  only  in 
1900,  has  during  the  first  three  years  produced  over  13,000,000 
worth  of  gold.  The  district,  which  lies  in  the  arid  desert 


* 


FIG.  76.  — Ideal  cross  section  of  rocks  at  Tonopah,  Nev.     After  Spurr,  U.S. 
Geol.  Surv.,  Bull.  225:  108. 

region  of  Nevada,  contains  a  series  of  Tertiary  lavas  and  tuffs, 
the  former  including  andesites,  dacites,  rhyolites,  and  basalt 
(Fig.  76).  The  earlier  lavas  and  tuffs  have  been  broken  by 
a  complex  series  of  faults  which  have  not,  however,  affected 
the  older  dacites  and  closely  associated  rhyolite  necks.  Four 
periods  of  vein  formation  have  been  discovered  closely  fol- 
lowing periods  of  eruption,  and  of  these  only  the  oldest, 
namely,  those  found  in  the  earlier  andesite,  are  available 
sources  of  ore.  The  veins,  which  have  been  formed  by 
replacement  in  sheeted  zones  and  show  more  or  less  de- 


344 


ECONOMIC   GEOLOGY   OF   THE   UNITED   STATES 


velopment  of  ore  shoots,  contain  quartz  with  orthoclase, 
and  inclose  as  metallic  minerals  stephanite  and  probably 
polybasite.  The  values  are  about  two  sevenths  gold  and 
five  sevenths  silver.  Subsequent  to  their  formation  they 
have  been  pierced  and  covered  by  later  volcanic  rocks, 
and  these,  together  with  the  complex  faulting,  has  pro- 
duced most  puzzling  structural  conditions.  The  Tonopah 
ore  deposits  are  analogous  genetically  to  the  Comstock 
lode  deposits  of  Nevada  (61). 


FIG.  77.  — Section  of  Comstock  lode.  D,  diorite;  Q,  quartz;  V,  vein  matter  in 
earlier  diabase  (Db) ;  H,  earlier  hornblende  andesite;  A,  augite  andesite. 
After  Seeker. 

Comstock  Lode,  Nevada.  —  This  lode,  which  is  of  historic 
interest,  occurs  near  Virginia  City,  in  southwestern  Ne- 
vada, and  is  a  great  fissure  vein,  about  four  miles  long,  sev- 
eral hundred  feet  broad,  and  branching  above,  following 
approximately  the  contact  between  eruptive  rocks,  and  dip- 
ping at  an  angle  of  35  to  45  degrees.  There  is  abundant 
evidence  of  faulting,  which  in  the  middle  portion  of  the  vein 
has  amounted  to  3000  feet.  The  lode  is  of  Tertiary  age, 
and  contains  silver  and  gold  minerals  in  a  quartzose  gangue. 


GOLD   AND   SILVER  345 

One  of  the  peculiar  features  of  the  deposit  is  the  extreme 
irregularity  of  the  ore,  which  occurs  in  great  "bonanzas," 
some  of  which  carried  several  thousand  dollars  to  the  ton. 
The  faulting  is  considered  to  have  been  quite  recent,  and 
the  high  temperatures  encountered  in  the  lower  levels  of 
the  mine  indicates  that  there  is  probably  a  partially  cooled 
mass  of  igneous  rock  at  no  great  depth. 

In  former  years  the  enormous  output  of  this  mine  caused  Nevada  to 
be  one  of  the  foremost  silver  producers.  It  was  discovered  as  early  as 
1858,  and  increased  until  1877,  after  which  it  declined.  Many  serious 
obstacles  were  met  with  in  the  development  of  the  mine,  such  that  it 
has  never  become  a  source  of  much  profit  in  spite  of  its  enormous  output. 
In  1863,  at  a  depth  of  3000  feet,  the  mine  was  flooded  by  water  of  a  tem- 
perature of  170°  F.,  due  to  a  break  in  the  clay  wall ;  and  to  drain  it 
$2,900,000  were  spent  in  the  construction  of  the  Sutro  tunnel,  which  was 
nearly  four  miles  long,  but  by  the  time  it  was  finished  the  workings  were 
below  its  depth.  A  second  difficulty  was  the  encountering  of  high  tem- 
peratures in  lower  workings,  these  in  the  drainage  tunnel  mentioned  being 
110°  to  114°  F.  The  mine  is  credited  with  a  total  production  of  $368,- 
000,000.  In  recent  years  its  output  has  been  slowly  increasing  again. 

Other  occurrences  of  the  propylitic  type  are  found  in  Gil- 
pin,  Boulder,  and  Clear  Creek  (48)  counties,  Colorado. 

In  Arizona  the  Commonwealth  Mine  of  Cochise  County 
is  probably  referable  to  this  group,  as  is  also  the  Congress 
Mine  (19,20). 

Fissure  veins  associated  with  Tertiary  eruptives  are 
found  in  Owyhee  County,  Idaho,  in  the  Monte  Cristo  dis- 
trict of  Washington  (88),  and  the  Bohemia  district  of 
Oregon  (70).  The  auriferous  copper  veins  of  Butte,  Mon- 
tana, also  belong  in  this  group,  but  since  they  are  more 
important  as  producers  of  copper,  they  are  described  under 
that  head. 


346          ECONOMIC   GEOLOGY   OF   THE   UNITED   STATES 

Auriferous  Gravels  (23,29,30). — These  form  an  important 
source  of  supply  of  gold,  together  with  a  little  silver,  and, 
although  widely  distributed,  become  prominent  chiefly  in 
those  areas  in  which  auriferous  quartz  veins  are  abundant. 
So,  while  they  are  found  in  many  parts  of  the  Cordilleran 
region,  in  the  Black  Hills,  and  in  the  Atlantic  States,  their 
greatest  development  is  in  the  Pacific  coast  belt  from  Cali- 
fornia up  to  Alaska. 

These  auriferous  gravels  represent  the  more  resistant 
products  of  weathering,  such  as  quartz  and  native  gold, 
which  have  been  washed  down  from  the  hills  on  whose 
slopes  the  gold-bearing  quartz  veins  outcrop,  and  were  too 
coarse  or  heavy  to  be  carried  any  distance,  unless  the  grade 
was  steep.  They  have  consequently  settled  down  in  the 
stream  channels,  the  gold,  on  account  of  its  higher  gravity, 
collecting  usually  in  the  lower  part  of  the  gravel  deposit. 

Although  the  gold-bearing  gravels  have  been  derived 
from  veins  of  varying  age,  the  deposition  of  the  gravel 
has  rarely  occurred  in  pre-Tertiary  times,  and  some,  indeed, 
are  of  very  recent  origin. 

The  gold  occurs  in  the  gravels  in  the  form  of  nuggets, 
flakes,  or  dustlike  grains,  the  last  being  usually  hard  to 
catch.  The  nuggets  represent  the  largest  pieces,  and  the 
finding  of  some  very  large  ones  has  been  recorded  from 
time  to  time  in  different  parts  of  the  world.  Two  large 
nuggets  are  recorded  from  Victoria :  one,  the  "  Welcome 
Stranger,"  weighing  2280  ounces  ;  and  the  other,  the  "  Wel- 
come Nugget,"  weighing  2166  ounces.  Since  the  auriferous 
gravels  of  the  Pacific  coast  belt  are  the  most  important, 
they  will  be  specially  referred  to. 

These  have  been  derived  from  the  wearing  down  of  the 


GOLD   AND  SILVER 


347 


Sierras,  and  are  found  in  those  valleys  leading  off  the 
drainage  from  the  mountains.  Many  were  formed  during 
the  Tertiary  period,  when  the  Sierras  were  subjected  to  a 
long- continued  denudation,  while  violent  volcanic  outbursts 
at  the  close  of  the  Tertiary  have  often  covered  the  gravels 
and  protected  them  from  subsequent  erosion.  These  lava 
cappings  are  at  times  150  to  200  feet  thick,  as  in  Table 
Mountain,  Tuolumne  County. 

Many  of  the  gravel  deposits  are  on  lines  of  former  drain- 
age, while  others  lie  in  channels  still  occupied  by  streams. 
Some  show  but  one  streak 
of  gold,  while  in  others 
there  may  be  several,  some 
of  which  are  on  rock 
benches  of  the  valley  bot- 
tom (Fig.  78). 

During   the   early  days 

of  gold  mining  111  Calif  Or-     FIG.  78.— Generalized  section  of  old  placer, 

with  technical  terms,    a,  volcanic  cap; 

nia  the  gravels  at  lower  b,  upper  lead;  c,  bench  gravel;  d,  chan- 
,  n  nel  gravel.  After  R.  E.  Browne. 

levels   and   in    the   valley 

bottoms  were  worked,  but  as  these  became  exhausted,  those 

farther  up  the  slopes  or  hills  were  sought. 

In  the  earlier  operations  the  gravels  were  washed  en- 
tirely by  hand,  either  with  a  pan  or  rocker,  and  this  plan 
is  even  now  followed  by  small  miners  and  prospectors; 
but  mining  on  a  larger  scale  is  carried  on  by  one  of  three 
methods,  viz.  drift  mining,  hydraulic  mining,  and  dredging. 

Drift  mining  is  employed  in  the  case  of  gravel  deposits 
covered  by  a  lava  cap,  a  tunnel  being  run  in  to  the  paying 
portion  of  the  bed  and  the  auriferous  gravel  carried  out 
and  washed. 


348          ECONOMIC   GEOLOGY   OF   THE  UNITED   STATES 

In  hydraulic  mining,  a  stream  is  directed  against  the 
bank  of  gravel  and  the  whole  washed  down  into  a  rock 
ditch  lined  with  tree  sections,  or  into  a  wooden  trough 
with  cross  pieces  or  riffles  on  the  bottom.  The  gold,  being 
heavy,  settles  quickly  and  is  caught  in  the  troughs  or 
ditches,  while  the  other  materials  are  carried  off  and  dis- 
charged into  some  neighboring  stream.  Mercury  is  some- 
times put  behind  the  riffles  to  aid  in  catching  the  gold. 

The  water  which  is  used  to  wash  down  the  gravel  de- 
posits is  often  brought  a  long  distance,  sometimes  many 
miles,  and  at  great  expense,  bridging  valleys,  passing 
through  tunnels,  and  even  crossing  divides,  this  being 
done  to  obtain  a  large  enough  supply  as  well  as  a  sufficient 
head  of  water. 

Owing  to  the  great  amount  of  debris  which  was  swept 
down  into  the  lowlands,  a  protest  was  raised  by  the  farm- 
ers dwelling  there,  who  claimed  that  their  farms  were 
being  ruined;  and  it  soon  became  a  question  which  should 
survive,  the  farmer  or  the  miner,  for  in  places  the  gravels 
and  sand  from  the  washings  choked  up  streams  and  accu- 
mulated to  a  depth  of  70  or  80  feet.  The  question  was 
settled  in  1884  in  favor  of  the  farmer  by  an  injunction, 
issued  by  the  United  States  Circuit  Court,  which  caused 
many  of  the  hydraulic  mines  to  suspend  operations;  and 
at  a  later  date  this  was  extended  by  state  legislation, 
adverse  to  the  hydraulic  mining  industry.  Owing  to  this 
setback,  hydraulic  mining  fell  to  a  comparatively  unim- 
portant place  in  the  gold-producing  industry  of  California, 
while  at  the  same  time  quartz  mining  increased. 

The  passage  of  the  Caminetti  law  now  permits  hydraulic 
mining,  but  requires  that  a  dam  shall  be  constructed  across 


PLATE  XXII 


FiG.  1.  —  Hydraulic  mining  of  auriferous  gravel.    The  sluice  box  in  the  foreground 
is  for  catching  the  gold. 


Fro.  2.  —  An  Alaskan  placer  depos 


GOLD   AND   SILVER  349 

the  stream  to  catch  the  tailings.  This  resulted  in  a  revival 
of  the  industry. 

Dredging  consists  in  taking  the  gravel  from  the  river 
with  some  form  of  dredge.  The  method,  which  was  first 
practised  in  New  Zealand,  has  been  introduced  with  great 
success  into  California,  especially  on  the  Feather  River, 
near  Oroville,  and  its  use  has  spread  to  other  parts  of  the 
Cordilleran  region.  The  gravel  when  taken  from  the  river 
is  discharged  on  to  a  screen,  which  separates  the  coarse 
stones,  and  the  finer  particles  pass  over  amalgamated  plates, 
tables  with  riffles,  and  then  over  felt. 

Formerly  much  placer  gold  was  obtained  by  hydraulic 
mining,  but  the  annual  supply  from  this  source  is  slowly 
decreasing,  as  is  that  from  drift  mining,  while  the  returns  of 
dredger  gold  have  been  continually  increasing  since  1900, 
being  1200,000  in  that  year  and  $1,500,000  in  1903.  This  is 
due  to  the  fact  that  large  areas  in  Yuba,  Sutler,  Nevada,  Butte, 
and  Sacramento  counties  have  been  found  adapted  to  dredg- 
ing processes,  while  the  improvement  and  enlargement  of  the 
dredging  machines  has  greatly  decreased  the  cost  of  mining. 

Placer  gold  is  also  worked  in  Idaho,  Montana,  Oregon,  New 
Mexico,  and  Colorado,  all  of  the  deposits  except  those  of  the 
last  two  states  having  been  derived  mostly  from  Mesozoic  veins. 

Gold  also  occurs  in  beach  sand  of  certain  portions  of  the 
Pacific  coast  of  Washington  (86),  and  placer  mining  has  been 
carried  on  since  1894 ;  but  the  supply  of  gold,  which  is  ob- 
tained from  Pleistocene  sands  and  gravels,  is  small. 

In  arid  regions  where  the  gold-bearing  sands  are  largely 
the  product  of  disintegration,  and  water  for  washing  out  the 
metal  is  wanting,  a  system  known  as  dry-blowing  is  some- 
times resorted  to. 


350 


ECONOMIC   GEOLOGY   OF   THE   UNITED   STATES 


BLACK  HILLS  REGION 

The  gold-bearing  ores  are  found  chiefly  in  the  northern 
Black  Hills,  and  include  (1)  auriferous  schists  in  pre- 
Cambrian  rocks;  (2)  Cambrian  conglomerates;  (3)  re- 
fractory siliceous  ores;  (4)  high-grade  siliceous  ores;  and 
(5)  placers.  Of  these  the  first  and  third  are  the  most 
important. 

The  surface  placers,  being  the  most  easily  discovered,  were 
developed  first,  followed  by  the  conglomerates  at  the  base  of 


J  CEMENT  MINES 


FIG.  79.  —  Section  of  Homestake  belt  at  Lead,  S.  Dak.,  showing  relation  of  ancient 
and  modern  placers  to  Homestake  lode.     From  Min.  Mag.  XI:  467. 

the  Cambrian.  These  are  found  near  Lead,  occupying  depres- 
sions in  the  old  schist  surface,  and  the  material  is  thought 
to  have  been  derived  from  the  reef  formed  by  the  Homestake 
ledge  in  the  Cambrian  sea.  These  deposits  are  of  interest 
as  being  probably  the  oldest  gold  placers  known  in  the 
United  States.  The  fact,  however,  that  the  matrix  of  the 
gold-bearing  portion  of  the  conglomerate  is  pyrite  rather 
than  quartz,  and  the  occurrence  of  the  gold  along  fractures 
stained  by  iron,  has  led  some  to  believe  that  the  gold  has 
been  precipitated  chemically  by  the  action  of  iron  sulphide 
and  is  not  a  detrital  product. 


ROBERT  W.  WEBB 
GEOLOGY  DEPT.,  U.C.LA 


PLATE  XXIII 


GOLD   AND   SILVER 


351 


Homestake  Belt.  —  The  gold  ores  of  the  Hornestake  belt 
(76,  77),  which  are  the  most  important  in  the  Black  Hills,  oc- 
cur in  a  broad  zone  of  impregnated  schists,  containing  many 
quartz  lenses,  alternating  with  dikes  of  fine-grained  rhyolite, 
which  also  formed  sheets  in  the  Cambrian  sediments  over- 
lying the  schists,  and  now  remain  as  a  resistant  cap  on  many 
of  the  surrounding  ridges.  The  ore,  which  is  all  low  grade, 
averaging  $5  to  $6  per  ton,  is  usually  a  mixture  of  quartz, 


CONGLOMERATE 


Pio.  80.— Typical  section  of  siliceous  gold  ores,  Black  Hills,  S.  Dak.    After 
Irving,  U.  S.  Geol.  Surv.,  Prof.  Pap.  26. 

pyrite,  and  occasionally  other  minerals  having  no  definite 
connection  with  it,  occupying  a  zone  in  the  Algonkian  rocks 
which  shows  greater  hardness,  irregularity  of  structure,  and 
mineralization  than  the  surrounding  schists.  The  boundaries 
are  poorly  defined,  and  superficial  examination  may  fail  to 
distinguish  between  ore  and  barren  rock.  In  the  upper  levels 
the  ore  seems  to  be  with  the  dikes,  but  diverges  from  them 
in  depth,  and  there  is  apparently  no  genetic  relation  between 
the  two.  In  the  earlier  days  the  ore  encountered  was  oxidized 
and  free-milling,  but  the  appearance  of  sulphides  with  depth 


352          ECONOMIC   GEOLOGY   OP  THE  UNITED   STATES 

has  necessitated  the  introduction  of  the  cyanide  method  of 
extraction.  In  spite  of  the  low  grade  of  its  ores  the  Home- 
stake  mine,  due  to  proper  management,  stands  out  as  one 
of  the  richest  mines  of  the  world,  its  monthly  production 
amounting  to  about  $ 300,000  (Curie).  The  ore  was  origi- 
nally worked  as  an  open  cut  (PL  XXIII),  but  later  by 
underground  methods. 

Siliceous  Cambrian  Ores.  —  A  second  important  type  is 
the  refractory  siliceous  Cambrian  ore  found  in  the  region 
between  Yellow  Creek  and  Squaw  Creek,  and  yielding  about 
two  thirds  as  much  gold  as  the  Homestake.  The  deposits, 
which  occur  as  replacements  in  a  siliceous  dolomite,  are  found 
at  two  horizons,  one  immediately  overlying  the  basal  Cam- 
brian quartzite,  and  the  other  near  the  top  of  the  Cambrian 
series.  The  ore  forms  flat  banded  masses  known  as  shoots, 
and  varying  in  width  from  a  few  inches  to  300  feet.  It  is 
overlain  by  shale  or  eruptive  rock,  and  associated  with  a 
series  of  vertical  fractures,  made  prominent  by  a  slight  silici- 
fication  of  the  wall  rock.  These  fractures,  which  are  termed 
verticals,  are  supposed  to  have  conducted  the  ore-bearing 
solutions. 

The  ore  is  a  hard,  brittle  rock,  composed  of  secondary 
silica,  with  pyrite  and  fluorite,  and  at  times  barite,  wolfram- 
ite, stibnite,  and  jarosite.  Its  contents  range  from  $3  or  $4 
per  ton  to  in  rare  cases  $100  per  ton,  with  an  average  of 
$17.  Other,  but  less  important,  siliceous  ores  occur  in  the 
Carboniferous  rocks. 

Michigan  Region  (55).  — A  small  amount  of  gold  has  been 
found  in  a  quartzose  zone  in  schists,  near  Marquette,  Mich- 
igan, but  the  area  is  of  little  importance. 

Eastern  Crystalline  Belt  (82) .  —  Gold,  with  some  silver,  has 


GOLD   AND   SILVBB  353 

been  found  in  the  rocks  of  this  belt  from  Vermont  to  Alabama, 
but  the  deposits  are  of  little  importance  except  in  North 
Carolina  (68),  South  Carolina  (74),  Georgia  (49,  50),  and  Ala- 
bama (3).  In  this  belt  the  ore  occurs  as  auriferous  pyrite, 
in  quartz  veins,  as  impregnations  in  metamorphic  rocks,  or 
in  placers  derived  from  either  of  the  foregoing  groups.  The 
last-named  type  is  practically  exhausted.  Of  the  other  types, 
there  are  many  occurrences,  in  all  of  which  the  ore  exists  in 
variable  quantities,  but  is  of  very  low  grade,  so  that  to  be 
profitable  the  deposits  must  be  worked  on  a  large  scale  by 
proper  methods.  In  many  localities  the  free  gold  of  the 
oxidized  portion  of  the  ore  body  has  been  worked  out  and 
the  mine  abandoned. 

The  deposits  are  in  many  instances  associated  with  in- 
trusives,  some  of  which  are  metamorphosed,  still  they  bear 
no  genetic  relation  to  them,  being  frequently  of  later  origin. 
They  are  usually  classed  as  pre-Cambrian,  but  some  may  be 
of  later  age. 

Alaska  (14).  —  Although  gold  has  been  known  to  occur 
in  Alaska  since  the  early  part  of  the  century,  and  was 
even  worked  in  1860,  its  production  is  not  definitely  stated 
until  1880,  when  it  was  added  to  the  list  of  gold-producing 
regions,  with  an  output  of  $6000,  which  since  that  time  has 
increased  many  times  over,  but  not  steadily,  until  in  1903  it 
amounted  to  $8,614,700. 

The  first  gold  was  discovered  on  the  islands  of  the  Alex- 
ander Archipelago  and  along  the  adjoining  coast,  but  sub- 
sequently prospectors  found  their  way  into  the  interior,  the 
first  strikes  there  being  made  in  British  Columbia  near  the 
head  of  the  Stikine  River.  These  were  followed  by  di§- 
coveries  in  the  Yukon  Valley,  especially  along  some  of  the 


354 


ECONOMIC   GEOLOGY   OF   THE  UNITED   STATES 


tributaries  known  as  Birch  Creek,  Mission  Creek,  and 
Forty  Mile  Creek.  In  1896  still  richer  discoveries  were 
made  along  the  Klondike  River,  and  within  one  year  the 
yield  of  this  region  had  exceeded  the  purchase  price  of 
Alaska.  Other  discoveries  have  since  followed  rapidly. 
The  gold  deposits  of  Alaska  are  of  two  types,  viz.  quartz 


FIG.  81.  —  Map  showing  mineral  deposits  of  Alaska  as  far  as  known.    After 
Brooks,  U.  S.  Geol.  Surv.,  Bull.  259. 

veins  and  placers.  The  former  are  prominent  along  the 
coast,  and  the  most  important  producer  is  the  Treadwell 
group  of  mines  on  Douglas  Island,  southeast  of  Juneau  (14). 
The  geology  of  this  region  bears  in  many  ways  a  strong 
resemblance  to  the  California  gold  belt,  and  is  probably  of 
similar  age.  The  section  involves  a  series  of  steeply  dipping 
slates  and  greenstone  and  diorite  dikes  (Fig.  83).  The  ore 


GOLD   AND   SILVER 


355 


bodies  are  dikes  of  albite-diorite,  permeated  with  metallic 
sulphides  and  carrying  small  amounts  of  gold  (14),  with  a 
hanging  wall  of  greenstone  and  a  foot  wall  of  black  slate. 
The  veinlets,  which  are  thought  to  have  been  formed  by 
shearing  stresses  incident  to  epeirogenic  movements,  occur 
in  two  sets  of  fractures  at  right  angles  to  each  other. 
Spencer  believes  that  the  mineralization  has  been  caused 
by  hot  ascending  solutions  of  possibly  magmatic  origin. 


FIG.  82.  —  Sketch  map  of  Douglas  Island,  Alaska.    After  Spencer,  U.  S.  Geol. 
Surv.,Bull.259:71. 

Secondary  concentration  is  not  in  evidence,  and  it  is 
thought  that  the  depth  to  which  the  ores  can  be  worked 
will  depend  more  on  the  increased  cost  of  mining  at  great 
depths  rather  than  on  exhaustion  of  the  ore.  At  present 
an  almost  continuous  ore  body  has  been  developed  for 
3500  feet. 

The  placer  deposits  have  been  found  in  many  parts  of 
Alaska,  but  the  two  regions  which  have  yielded  the  largest 
amount  are  the  Yukon  region  (16)  and  the  Seward  Penin- 
sula (14,  15),  the  latter  being  now  the  first. 


356          ECONOMIC   GEOLOGY   OF   THE   UNITED   STATES 

Gold  was  discovered  in  the  Forty  Mile  district  of  the 
Yukon  in  1886,  and  caused  a  stampede  for  this  region;  but 
the  deposits  of  the  Klondike  did  not  become  known  until 
1896,  and  their  discovery  was  followed  by  a  rush  of  gold 
seekers  that  eclipsed  all  previous  ones.  Indeed,  it  is  said 
that  by  1898  over  40,000  people  were  camped  out  in  the 
vicinity  of  the  present  site  of  Dawson. 

The  Klondike  region  proper  is  situated  on  the  eastern 
side  of  the  Yukon  River,  and  the  richer  deposits  found 
have  been  on  the  Canadian  side  of  the  boundary.  The 


SCALE  1,050  FEET=1    INCH 


ED    M\ 


FIG.  83.  —  Cross  section  through  Alaska  Tread  well  mine  on  northern  side  of 
Douglas  Island.    After  Spencer,  U.  S.  Geol.  Surv.,  Bull.  259 

gold  has  collected  either  at  the  bottom  of  the  gravel  in  the 
smaller  streams  tributary  to  the  Yukon,  or  else  in  gravels 
on  the  valley  sides,  this  latter  occurrence  being  known  as 
bench  gravel.  The  metal  is  supposed  to  have  been  derived 
from  the  quartz  veins  found  in  the  Birch  Creek,  Forty  Mile, 
and  Rampart  series  of  metamorphic  rocks  lying  to  the  east. 
Up  to  the  end  of  1902  the  total  production  of  the  Klondike 
is  stated  to  have  been  $80,000,000.  The  annual  output  has, 
however,  decreased,  and  mining  in  that  region  has  settled 
down  to  a  more  permanent  basis.  Gravels  running  under 
$9  per  cubic  yard  cannot  be  worked  at  a  profit,  because  the 
difficulties  and  expenses  of  running  in  such  a  region  are 


GOLD   AND   SILVER  357 

great,  and  form  an  interesting  comparison  with  conditions 
in  California,  where  gravel  carrying  25  cents  per  yard  is 
considered  good,  while  that  running  as  low  as  5  cents  per 
yard  can  be  worked  (18). 

Since  the  discovery  of  the  rich  gold  gravels  on  the  Yukon, 
auriferous  gravels  have  been  developed  in  many  other  parts 
of  Alaska,  where  they  are  being  more  or  less  actively  worked 
(Fig.  81),  but  of  these  various  finds  those  in  the  Seward 
Peninsula,  which  is  now  the  largest  producer,  have  been 
the  most  important. 

The  first  of  the  localities  discovered  in  the  last-mentioned 
region  was  Cape  Nome  (15),  which  for  a  time  proved  to  be  a 
second  Klondike.  The  gold  was  discovered  here  on  Anvil 
Creek,  and  the  following  year  in  the  beach  sands  where 
Nome  now  stands.  These  discoveries  caused  another  north- 
ward stampede,  which  resulted  in  the  rapid  exhaustion  of 
the  beach  sands ;  but  other  deposits  were  found  farther 
inland  near  Nome,  as  well  as  the  other  localities  on  the 
Seward  Peninsula.  Some  quartz  veins  are  also  worked. 
Ophir  Creek  is  now  the  largest  producer  on  the  Seward 
Peninsula.  Up  to  the  end  of  1902  the  Seward  Peninsula 
had  produced  $20,000,000  in  gold,  and  in  1903  the  produc- 
tion of  the  Nome  region  is  given  as  $4,437,449. 

Uses  of  Gold.  —  Gold  is  chiefly  used  for  coinage,  orna- 
ments, and  ornamental  utensils.  It  is  also  employed  to 
a  considerable  extent  in  dentistry  and  in  an  alloy  for  the 
better  class  of  gilding. 

Its  value  for  use  in  the  arts  depends  on  its  brightness, 
freedom  from  tarnish,  and  its  ductility  and  malleability, 
which  permit  it  to  be  easily  worked.  As  pure  24-carat 


358 


ECONOMIC   GEOLOGY   OF   THE   UNITED   STATES 


gold  is  too  soft  for  use,  it  is  alloyed  with  a  small  amount 
of  some  other  metal,  such  as  copper,  to  gain  hardness. 

Uses  of  Silver.  —  This  metal  was  formerly  of  much  im- 
portance for  coinage,  but  is  much  less  so  now.  It  is, 
however,  widely  employed  in  the  arts  for  making  jewelry 
and  utensils  such  as  tableware.  Its  salts  are  of  more 
or  less  value  in  medicine  and  in  photography.  Its  bright- 
ness and  white  color  are  valuable  properties  when  the  metal 
is  used,  but,  unlike  gold,  it  tarnishes  somewhat  readily  when 
exposed  to  sulphurous  gases.  There  are  a  number  of  alloys 
of  silver,  those  with  gold  and  copper,  respectively,  being 
of  importance. 

Production  of  Gold  and  Silver  :  — 

PRODUCTION  OF  GOLD  AND  SILVER  IN  THE  UNITED  STATES  FROM 
1845  TO  1903 


YKAR 

TOTAL 

GOLD 

SILVER 
(Coining  Value) 

1845  

$1,058,327 

$1,008,327 

$50,000 

1855 

55  050  000 

55  000  000 

50000 

1865  

64,475,000 

53,225,000 

11,250,000 

1875    .  . 

65  100  000 

33,400  000 

31  700  000 

1885  

83,400,000 

31,800,000 

51,600,000 

1895  

118,661  000 

46  610  000 

72,051,000 

1900 

153  704  495 

79  171  000 

74  533  495 

1901  

150  054  500 

78  666  700 

71,387,800 

1902 

151  757  575 

80  000  000 

71  757  575 

1903  

143,797,760 

73,591,700 

70,206,060 

The  production  by  states  for  1903  is  given  below,  and 
shows  well  the  overwhelming  importance  of  the  Cordil- 
leran  region:  — 


GOLD   AND   SILVER 


359 


PRODUCTION  AND  VALUE  OF  GOLD  AND  SILVER  IN  THE  UNITED 
STATES  IN  1903,  BY  STATES 


GOLD 

SILVER 

TOTAL 

(Silver  at 

r           *  i 

Commercial 

Quantity 

Value 

Quantity 

Value 

Value) 

Fine  oz. 

Dollars 

Fine  oz. 

Dollars 

Dollars 

Alabama     .     . 

213 

4,400 

4,400 

Alaska    .     .     . 

416,738 

8,614,700 

143,600 

77,544 

8,692,244 

Arizona  .     .     . 

210,799 

4,357,600 

3,387,100 

1,879,034 

6,186,634 

California    .     . 

779,057 

16,104,500 

931,500 

503,010 

16,607,510 

Colorado     .     . 

1,090,376 

22,540,100 

12,990,200 

7,014,708 

29,554,808 

Georgia  .     .     . 

3,000 

62,000 

400 

216 

62,216 

Idaho      .     .     . 

75,969 

1,570,400 

6,507,400 

3,513,996 

5,084,396 

Kansas    .     .     . 

468 

9,700 

97,400 

52,596 

62,296 

Maryland    .     . 

24 

500 

500 

Michigan     .     . 

50,000 

27,000 

27,000 

Montana      .     . 

213,425 

4,411,900 

12,642,300 

6,826,842 

11,238,742 

Nevada   .     .     . 

163,892 

3,388,000 

5,050,500 

2,727,270 

6,115,270 

New  Mexico    . 

11,833 

244,600 

180,700 

97,578 

342,178 

North  Carolina 

3,411 

70,500 

11,000 

5,940 

76,440 

Oregon    .     .     . 

62,411 

1,290,200 

118,000 

63,720 

1,353,920 

South  Carolina 

4,872 

100,700 

300 

162 

100,862 

South  Dakota  . 

330,243 

6,826,700 

221,200 

119,448 

6,946,148 

Tennessee   .     . 

38 

800 

13,000 

7,020 

7,820 

Texas      .     .    . 

454,400 

245,376 

245,376 

Utah  .... 

178,863 

3,697,400 

11,196,800 

6,046,272 

9,243,672 

Virginia      .     . 

654 

13,500 

9,500 

15,130 

18,630 

Washington     . 

13,539 

297,900 

294,500 

159,030 

438,930 

Wyoming    .     . 

175 

3,600 

200 

108 

3,708 

Total    .     . 

3,560,000 

73,591,700 

54,300,000 

29,322,000 

102,913,700 

Mr.  Lindgren  (80)  has  recently  given  a  most  interesting 
and  valuable  classification  of  the  figures  of  gold  and  silver 
production,  grouped  according  to  the  kind  of  ores  from 
which  they  have  been  derived.  These  are  given  below, 
and  indicate  that  the  Tertiary  quartz  veins  yield  the 
largest  amount  of  gold,  and  the  lead  ores  the  greatest 
quantity  of  silver. 


360 


ECONOMIC   GEOLOGY   OF   THE   UNITED   STATES 


PRODUCTION  OF  GOLD  AND  SILVER  IN  1904  ACCORDING  TO 
KINDS  OF  ORE 


GOLD 
FINE  OUNCES 

SILVER 
FINE  OUNCES 

Placers 

619  700 

64  000 

Quartzose  gold  and  silver  ores  — 
Pre-Cambrian  quartz  veins      
Mesozoic  quartz  veins     

264,000 
1  045  000 

79,000 
860  000 

1  727  000 

11  000  000 

Copper  ores    

206  000 

18  600  000 

22°  500 

23  000  000 

4,086,200 

53,603,000 

WORLD'S  PRODUCTION  OF  GOLD  AND  SILVER  IN  1903 


GOLD 

SILVER 

TOTAL 

North  and  Central  America  . 
Australia      

$104,979;000 
89  210,100 

$70,235,500 
5  228,700 

$175,214,500 
94,438,800 

Africa 

67  998  100 

185  300 

68  183  400 

27,117,800 

8  182  100 

35  299,900 

25  434  000 

359  100 

25  793  100 

South  America      

10  788  200 

7  848  900 

18,637,100 

Total     

$325,527,200 

$92,039,600 

$417,566,800 

REFERENCES  ON  GOLD  AND  SILVER 

GENERAL.  1.  Blake,  Amer.  Inst.  Min.  Engrs.,  Trans.  XXVI :  290, 1897. 
(Gold  in  igneous  rocks.)  2.  Cumenge  and  Robellaz,  L'Or  dans  la 
nature  (Paris,  1898).  3.  Curie,  The  Gold  Mines  of  the  World 
(London,  1902).  4.  Don,  Amer.  Inst.  Min.  Engrs.,  Trans.  XXVII : 
564,  1898.  (Genesis  of  certain  auriferous  lodes.)  5.  Emmons, 
Amer.  Inst.  Min.  Engrs.,  Trans.  XVI :  804,  1888.  (Structural  rela- 
tions of  ores.)  6.  Kemp,  Min.  Indus.,  VI :  295,  1898.  (Telluride 
ores.)  7.  Liversidge,  Amer.  Jour.  Sci.,  XLIII :  245, 1892.  8.  Mer- 
rill, Amer.  Jour.  Sci.,  1 :  309,  1896.  (Gold  in  granite.)  9.  Pearce, 
Ores  of  Gold,  etc.,  Colo.  Sci.  Soc.  Proc.,  Ill:  237.  10.  Rickard, 
Min.  and  Sci.  Pr.,  LXXVII:  81  and  105,  1898.  (Minerals  ac- 


GOLD  AND  SILVER  861 

companying  gold.)  11.  Spurr,  Eng.  and  Min.  Jour.,  LXXVI : 
500,  1903.  (Gold  in  diorite.)  12.  Spurr,  Eng.  and  Min.  Jour., 
LXXVII :  198,  1904.  (Native  gold  original  in  metamorphic  gneis- 
ses.) —  Alabama :  13.  Brewer,  Ala.  Geol.  Surv.,  Bull.  5,  1896;  Phil- 
lips, Ala.  Geol.  Surv.,  Bull.  3,  1892.  —  Alaska :  14.  Brooks  and 
others,  U.  S.  Geol.  Surv.,  Bull.  259,  1905.  (Mineral  resources.) 
15.  Schrader  and  Brooks,  Amer.  Inst.  Min.  Engrs.,  Trans.  XXX: 
236,  1901.  (Cape  Nome.)  16.  Spurr,  U.  S.  Geol.  Surv.,  18th  Ann. 
Kept.,  Ill :  101, 1898.  (Yukon  district.)  17.  See  also  various  papers 
on  Alaska  in  U.  S.  Geol.  Surv.,  Bull.  213,  1903,  and  Bull.  225,  1904. 
18.  Penrose,  Eng.  and  Min.  Jour.,  LXXVI:  807,  852,  1903.— 
Arizona :  19.  Blandy,  Amer.  Inst.  Min.  Engrs.,  Trans.  XI :  286, 1883. 
(Prescott  district.)  20.  Comstock,  Amer.  Inst.  Min.  Engrs.,  Trans. 
XXX:  1038,  1901.  (Geology  and  vein  phenomena.)  21.  Pratt, 
Eng.  and  Min.  Jour.,  LXXIII :  795,  1902.  Literature  on  Arizona 
gold  ores,  especially  of  recent  character,  is  scarce.  22.  See  reports 
of  Director  of  Mint.  —  California:  23.  Browne,  Calif.  State  Min. 
Bur.,  10th  Ann.  Kept.:  435.  (River  gravels.)  24.  Diller,  U.  S. 
Geol.  Surv.,  Bull.  260 :  45,  1905.  (Indian  Valley  region.)  25.  Fair- 
banks, Calif.  State  Min.  Bur.,  X:  23,  1890,  and  XIII:  665,  1896. 
(Mother  Lode  district.)  26.  Lindgren,  U.  S.  Geol.  Surv.,  17th  Ann. 
Kept.,  II :  1, 1896.  (Nevada  City  and  Grass  Valley.)  27.  Liiidgren, 
Geol.  Soc.  Amer.,  Bull.  VI:  221,  1895.  (Gold  quartz  veins.) 
28.  Lindgren,  U.  S.  Geol.  Surv.,  14th  Ann.  Kept.,  II:  243,  1894. 
(Ophir.)  29.  Lindgren,  U.  S.  Geol.  Surv.,  Bull.  213:  64,  1903. 
(Neocene  river  gravels.)  30.  Turner,  Amer.  Geol.,  XV :  371,  1895. 
(Auriferous  gravels.)  31.  See  also  various  annual  reports  of  Calif. 
State  Mineralogist.  —  Colorado :  32.  Comstock,  Amer.  Inst.  Min. 
Engrs.,  Trans.  XV:  218,  1886,  and  XI:  165,  1882.  (Geology  and 
vein  structure,  southwestern  Colo.)  33.  Emmons,  Eng.  and  Min. 
Jour.,  XXXV :  332,  1883.  (Summit  district.)  34.  Emmons,  U.  S. 
Geol.  Surv.,  17th  Ann.  Kept.,  II :  405, 1896.  (Custer  Co.)  35.  Farish, 
Colo.  Sci.  Soc.,  Proc.  IV :  151,  1892.  (Rico.)  36.  Irving,  U.  S. 
Geol.  Surv.,  Bull.  260 :  50,  1905.  (Ouray.)  37.  Irving,  U.  S.  Geol. 
Surv.,  Bull.  260 :  78, 1905.  (Lake  City.)  38.  Kedzie,  Amer.  Inst.  Min. 
Engrs., Trans.  XVI:  570,1888.  (RedMt.)  39.  Lindgren  and  Ran- 
some,  U.  S.  Geol.  Surv.,  Bull.  246, 1905.  (Cripple  Creek.)  40.  Pen- 
rose  and  Cross,  U.  S.  Geol.  Surv.,  16th  Ann.  Rept.,  II :  111,  1895. 
(Cripple  Creek.)  41.  Porter,  Amer.  Inst.  Min.  Engrs.,  Trans.  XXVI  : 
449, 1897.  (Telluride.)  42.  Purington,  U.  S.  Geol.  Surv.,  18th  Ann. 
Rept.,  Ill :  751, 1898.  (Telluride.)  43.  Ransome,  U.  S.  Geol.  Surv., 
Bull.  182,  1901.  (Silverton.)  44.  Rickard,  Min.  Indus.,  II:  325, 
1894,  and  IV :  315,  1896.  45.  Rickard,  Amer.  Inst.  Min.  Engrs., 


362         ECONOMIC   GEOLOGY   OF  THE   UNITED   STATES 

Trans.  XXX :  367, 1901.  (Cripple  Creek.)  46.  Schwartz,  Amer.  Inst. 
Min.  Engrs.,  Trans.  XVIII :  139, 1890.  (Cripple  Creek.)  47.  Skewes, 
Amer.  Inst.  Min.  Engrs.,  Trans.  XXVI :  553, 1897.  (Cripple  Creek.) 
48.  Spurr,  U.  S.  Geol.  Surv.,  Bull.  260 :  99,  1905.  (Georgetown.)  — 
Georgia  :  49.  Eckel,  U.  S.  Geol.  Surv.,  Bull.  213 :  57, 1903.  (Dahlonega 
district.)  50.  Yeates,  McCallie,  and  King,  Ga.  Geol.  Surv.,  Bull.  4  a, 

1896.  — Idaho:   51.   Lindgren,  U.S.  Geol.  Surv.,  20th  Ann.  Kept., 
Ill :  75,  1900.     (Silver  City,  De  Lamar  Co.)     52.   Lindgren,  U.  S. 
Geol.  Surv.,  18th  Ann.  Kept.,  Ill :  625,  1898.     (Idaho  Basin  and 
Boise  Ridge.)  — Kansas  :  53.  Lindgren,  Eng.  and  Min.  Jour.,  LXXIV : 
111,  1902.      (Tests   for   gold    and   silver  in  shales.)  —  Maryland  : 
54.  Weed,  U.  S.  Geol.  Surv.,  Bull.  260 :  128,  1905.     (Great  Falls.) 

—  Michigan :  55.  Wadsworth,  Ann.  Kept.,  1892,  Mich.  State  Geologist. 

—  Minnesota :  56.   Winchell  and  Grant,  Minn.  Geol.  and  Nat.  Hist. 
Surv.,  XXIII :  36, 1895.   (Rainy  Lake  district.)  —  Montana :  57.  Lind- 
gren, U.  S.  Geol.  Surv.,  Bull.  213 :  66, 1903.    (Bitter  Root  and  Clear- 
water   Mts.)     58.   Weed,  U.  S.  Geol.   Surv.,   Bull.  213:   88,  1903. 
(Marysville.)     59.   Weed  and  Barrell,  U.  S.  Geol.  Surv.,  22d  Ann. 
Rept.,  II :  399,  1902.     (Elkhorn  district.)     60.   Weed  and  Pirsson, 
U.  S.  Geol.  Surv.,  18th  Ann.  Rept.,  Ill :  589,  1898.     (Judith  Mts.) 

—  Nevada:   61.   Becker,  U.  S.  Geol.  Surv.,  Mon.  Ill,  1882.     (Corn- 
stock  Lode.)    62.  Lord,  U.  S.  Geol.  Surv.,  Mon.  IV,  1883.    (Comstock 
mining.)     63.   Spurr,  U.  S.  Geol.  Surv.,    Prof.  Pap.  42,  and  Bull. 
260 :  140, 1905.    (Tonopah.)     64.  Spurr,  U.  S.  Geol.  Surv.,  Bull.  225  : 
118,  1904,  and  Bull.  260 :  132, 1905.    (Gold  fields.)     65.  Spurr,  U.  S. 
Geol.  Surv.,  Bull.  225:  111,  1904.    (Silver  Peak  quadrangle.)    66.  See 
also  annual  reports  of  Director  of  Mint.  —  New  England :  67.  Smith, 
U.  S.   Geol.   Surv.,   Bull.  225 :   81,  1904.     (Me.   and  Vt.)  —  North 
Carolina :  68.   Nitze  and  Hanna,  N.  Ca.  Geol.  Surv.,  Bulls.  3  and  10. 

—  Oklahoma:    69.    Bain,  U.  S.  Geol.   Surv.,  Bull.  225:  120,  1904. 
(Wichita  Mts.)  —  Oregon :  70.   Diller,  U.  S.  Geol.  Surv.,  20th  Ann. 
Rept.,  Ill:   7,  1900.     (Bohemia  district.)     71.   Kimball,  Eng.  and 
Min.  Jour.,  LXXIII:  889,  1902.    (Bohemia  district.)    72.  Lindgren, 
U.  S.  Geol.   Surv.,  22d  Ann.  Rept.,  II:    551,  1901.     (Blue   Mts.) 
73.   See  also  bulletin  on  Oregon  Mineral  Resources  issued  by  Uni- 
versity of  Oregon.  —  South  Carolina  :  74.   Thies  and  Mezger,  Amer. 
Inst.  Min.  Engrs.,  Trans.  XIX :  595,  1891.    (Haile  Mine.)    See  also 
No.  82.  —  South  Dakota:  75.  Carpenter,  Amer.  Inst.  Min.  Engrs., 
Trans.  XVII :  570,  1889.    76.  Irving,  U.  S.  Geol.  Surv.,  Bull.  225 : 
123,  1904,  and  U.  S.  Geol.  Surv.,  Prof.  Paper  26,  1904.     (N.  Black 
Hills.)     77.    O'Harra,  S.  Dak.  Geol.  Surv.,  Bull.  3,  1902.     (Black 
Hills.)     78.   Smith,  Amer.  Inst.  Min.  Engrs.,  Trans.  XXVI:  485, 

1897.  (Cambrian  ores.)  —  United  States:  79.  Lindgren,  Amer.  Inst. 


GOLD  AND  SILVER  363 

Min.  Engrs,  Trans.  XXXIII:  790,  1903.  (N.  Amer.  production 
and  geology.)  80.  Lindgren,  U.  S.  Geol.  Surv.,  Bull.  260 :  32,  1905. 
81.  Nitze  and  Wilkens,  Amer.  Inst.  Min.  Engrs.,  Trans.  XXV:  661, 
1896.  (Appalachians.)  82.  Pratt,  Eng.  and  Min.  Jour.,  LXXIV : 
241,  1902.  (S.  Appalachians.)  83.  Ransome,  Min.  Mag.,  X:  7, 

1904.  See  also  annual  reports  on  Precious  Metals,  issued  by  Director 
of  Mint,  the  Mineral  Resources  issued  by  U.  S.  Geol.  Survey,  the 
Mineral  Industry,  and  Census  Report  on  Mines  and  Quarries,  1902. 
—  Utah :  84.  Spurr,  U.  S.  Geol.  Surv.,  16th  Ann.  Kept.,  II :  343, 1895. 
(Mercur.)    See  also  annual  reports  of  Director  of  Mint,  all  of  which 
contain  much  general  information,  partly  of  statistical  character; 
also  references  under  Silver-Lead.     85.  Warren,  Eng.  and  Min.  Jour. 
LXVIII :  455,  1899.    (Daly-West  Mine.)  —  Vermont :  See  New  Eng- 
land.—Washington:  86.  Arnold, -U.  S.  Geol.  Surv.,  Bull.  260:  154, 

1905.  (Beach  placers.)     87.   Smith,  Eng.  and  Min.  Jour.,  LXXIII : 
379,  1902.     (Mt.  Baker  district.)     88.   Spurr,  U.  S.  Geol.  Surv.,  22d 
Ann.  Kept.,  II :  777,  1901.    (Monte  Cristo.) 


CHAPTER  XVIII 
SILVER-LEAD  ORES 

THE  Silver-Lead  Ores  form  a  large  class,  which  are  widely 
distributed  in  the  Cordilleran  region,  and  not  only  supply 
most  of  the  lead  mined  in  the  United  States,  but  in  ad- 
dition may  also  and  often  do  carry  variable  quantities  of 
silver,  gold,  and  copper. 

The  deposits  as  a  whole  present  a  variety  of  forms.  The 
associated  rocks  are  often  faulted,  and  the  ore  bodies  are 
commonly  oxidized  above  so  that  the  altered  portions  re- 
quire different  metallurgical  treatment  from  the  sulphide 
ores  found  below.  Secondary  enrichment  has  in  some  cases 
raised  the  grade  of  the  ore.  Deposits  of  this  class  are 
prominent  in  Colorado,  Idaho,  and  Utah,  but  are  also  known 
in  New  Mexico,  Montana,  Wyoming,  Nevada,  Arizona,  Cali- 
fornia, and  South  Dakota.  Idaho  is  the  largest  producer  of 
silver-lead  ores,  but  they  average  only  one  third  silver, 
while  those  of  Colorado  average  three  quarters  silver,  and 
those  of  Utah  about  two  thirds  silver.  A  few  of  the  more 
prominent  occurrences  are  mentioned. 

Leadville  District,  Colorado  (1,  7).  — This  region  lies  in  the 
Mosquito  range  at  the  headwaters  of  the  Arkansas  River  in 
south  central  Colorado,  while  the  town  of  Leadville  is  situ- 
ated in  an  old  lake  basin  on  the  west  side  of  the  range. 
The  latter  is  composed  of  crystalline  rocks,  Paleozoic  sedi- 


SILVER-LEAD   ORES  365 

ments,  and  igneous  intrusions,  the  last  in  part  conforming 
to  the  bedding  planes  of  the  sedimentary  rocks.  The 
Paleozoic  section  alone  is  over  5000  feet  and  involves  the 
following  members:  — 

Upper  Carboniferous  limestone      .     .  1000  to  1500  feet. 

Weber  shales  and  sandstone      .     .     .  2000  feet. 

Oldest  or  white  porphyry     ....  

Carboniferous   blue   limestone   (chief 

ore-bearing  stratum) 200  feet. 

Gray  porphyry 

g       .      jQuartzite     ......  40  feet. 

n  {  White  limestone   ....  160  feet. 

Cambrian  quartzite 150  to  200  feet. 

The  rocks  on  the  western  side  of  the  Mosquito  range  are 
folded  and  faulted,  this  having  taken  place  during  late  Cre- 
taceous times,  when  the  Rocky  Mountains  were  uplifted,  and 
subsequent  to  the  intrusion  of  the  igneous  rocks.  It  is  con- 
sidered that  the  latter  stimulated  the  ascension  of  the  ore- 
bearing  solutions,  the  ore  being  commonly  deposited  on  the 
under  side  of  the  porphyry  sheets  and  in  contact  with  the 
blue  Carboniferous  limestones.  Later  developments  have 
shown  its  presence  along  some  of  the  other  contacts.  The 
unaltered  ore  is  argentiferous  galena  with  some  native  gold, 
but  within  the  zone  of  oxidation  the  galena  is  changed  to 
carbonate  and  sulphate,  with  silver  chloride  and  at  times 
containing  considerable  limonite.  The  gangue  is  calcite, 
barite,  and  chert. 

The  older  mines  are  mostly  east  of  the  city  on  Fryer,  Car- 
bonate, and  Iron  Hill,  but  in  recent  years  the  continuation  of 
the  deposits  has  been  found  under  the  city. 


366 


ECONOMIC  GEOLOGY  OF  THE  UNITED  STATES 


\ 


The  origin  of  the  ores  has  been  discussed  by  several  geolo- 
gists, among  them  Emraons  and  Blow  (1,  7).  The  former 
believes  that  the  ores  were  originally  deposited  as  sulphides 
from  aqueous  solutions  ascending  from 
.  some  deep  source,  and  by  a  process  in- 
I  volving  metasomatic  interchange,  the 
I  ore-bearing  solutions  following  the  con- 
K|  tact  because  it  happened  to  form  a 
i>  good  channel. 

^         For  many  years  the  oxidized  ores  of 
^     the    Leadville    district    have    been   an 

0  important   source    of   material  for   the 

1  smelters;    but  latterly  the  silver   ores 
k     have  shown  signs   of  exhaustion,  and 

ill^    their    place    has   been  taken   to   some 
«     extent  by  the  discovery  of  gold  ore  to 

1  the  east  of  the  town,  as  well  as  of  zinc 
®     sulphides    at    greater   depths   and  the 
S     shipment  of  larger  quantities  of  iron 

and  manganese  ores  than  formerly. 

Even  in  former  years  Leadville  was  a  mining 
§  camp  of  great  importance,  having  indeed  given 
%  Colorado  its  first  serious  start  as  a  mining  state. 
|  From  an  area  of  about  a  square  mile  the  output 
|  of  silver  was  for  a  number  of  years  greater  than 
£  that  of  any  foreign  country  except  Mexico, 

2  and  during  the  same  period  the  production  of 
lead  was  nearly  equal  to  that  of  England  and 
greater  than   that  of  any  European  country 

excepting  Spain  and  Germany.  Although  regarded  originally  as  a 
silver  camp,  it  really  ceased  being  such  nearly  ten  years  ago,  and  is  now 
an  important  producer  of  at  least  eight  metals,  of  which  five  or  six  are 


SILVER-LEAD   ORES  367 

sometimes  all  obtained  from  the  same  group  of  properties.  It  will  thus 
be  seen  that  the  successful  marketing  of  one  may  affect  all  the  others. 
Leadville  began  as  a  gold  camp  in  1860,  when  a  placer  deposit  of  gold 
was  found  in  a  gulch  near  there  and  several  million  dollars'  worth  of 
metal  were  extracted,  resulting  in  the  establishment  of  a  flourishing 
town  called  Oro,  which,  however,  soon  lost  its  importance  when  the  gold 
began  to  be  exhausted.  Not  until  1875  was  the  carbonate  of  lead,  which 
has  since  been  so  important,  actually  recognized. 

That  Leadville  is  no  longer  entirely  a  lead-silver  camp  is  evident 
from  the  fact  that,  in  1901,  of  the  850,000  long  tons  of  ore  mined,  35,000 
tons  were  zinc  ores,  70,000  tons  manganese  iron  ores,  and  the  remainder 
lead  and  copper  smelting  ores. 

Aspen,  Colorado  (15).  —  Here  again  the  ores  are  oxidized 
and  occur  in  highly  folded  and  faulted  Carboniferous  lime- 
stone, although  the  section  involves  rocks  ranging  in  age  from 
Archaean  to  Mesozoic.  Two  quartz  porphyries,  one  at  the 
base  of  the  Devonian,  the  other  in  the  Carboniferous,  are 
present,  but  bear  no  special  relation  to  the  ore. 

At  the  close  of  the  Cretaceous  the  rocks  were  folded  into 
a  great  anticline,  with  a  syncline  on  its  eastern  limit,  which 
passed  into  a  great  fault  along  Castle  Creek  west  of  the 
mines.  Contemporaneous  with  the  folding  there  were  also 
produced  two  faults  parallel  to  the  bedding  of  the  Carbonif- 
erous dolomite,  while  at  the  same  time  much  cross  faulting 
occurred.  The  ore  is  found  chiefly  at  the  intersection  of 
these  two  sets  of  fault  planes,  and  Spurr  considers  that  the 
ore-bearing  solutions  followed  the  bed  faults.1 

On  account  of  the  intimate  association  of  the  dolomite, 
quartz,  and  barite  with  the  ore  their  origin  is  considered  as 
similar. 

1  Weed  has  suggested  that  this  accumulation  of  ore  at  the  intersection  of 
fault  planes  is  the  result  of  secondary  enrichment,  rather  than  of  primary 
concentration. 


368 


ECONOMIC  GEOLOGY  OF  THE  UNITED  STATES 


The   ores  are   peculiarly  free  from   other  metals  except 
lead,  and  the  rich  polybasite  (Ag9SbS6)  ores  of  Smuggler 

Mountain  do  not  contain 
even  this. 

The  mining  camp  of 
Aspen  started  in  1879, 
but  its  development  for 
a  time  was  much  re- 
tarded by  lawsuits.  The 
richer  ore  bodies  were 
not  discovered  until 
1884,  and  then  by  un- 
derground exploration, 
for  owing  to  the  heavy 
mantle  of  glacial  gravels 
their  outcrops  were  hid- 
den. Since  also  the 
ore  carries  no  iron  or 
manganese,  as  do  the 
Leadville  ores,  its  out- 
crop may  be  incon- 
spicuous. 

The  railroads  did  not 
reach  the  camp  until  1887, 
so  that  during  the  first  few 


J  GLACIAL  DRIFT 

}  WEBER  FORMATION 

loRE 

J  LEADVILLE  DOLOMITE 


l  PARTING  QUARTZITE 
l  YULE  FORMATION 
l  SAWATCH  FORMATION" 
|  GRANITE 


*M  QUARTZ  PORPHYRY 

FIG.  85.— Section  of  ore  body  at  Aspen,  Colo. 
After  Spurr,  U.S.  Geol.  Surv.,  Mon.  XXXI. 


years  of  its  history  the  ore  had  to  be  carried  out  on  burros. 

In  both  Aspen  and  Smuggler  mountains  long  tunnels  have  been  run 
for  drainage  and  hauling  purposes.  The  Cowenhoven  tunnel,  which  is 
the  largest  of  these,  is  over  8300  feet  long,  and  taps  a  number  of  mines. 
Aspen  was  one  of  the  first  mining  camps  in  the  West  to  install  electric 
machinery  for  hoisting,  haulage,  etc.,  and  the  current  was  cheaply  sup- 
plied by  the  neighboring  water  power.  One  shaft  1000  feet  deep  is 
operated  electrically. 


PLATE  XXIV 


FIG.  1.  —  General  view  of  Rico,  Colo.,  and  Enterprise  group  of  mines. 


FIG.  2.  — Ontario  mine,  Park  City,  Utah. 


SILVER-LEAD   ORES 


369 


At  the  present  day  the  larger  ore  bodies  are  worked  out,  but  the  camp 
is  still  an  active  producer.  From  1881  to  1895  it  produced  $63,653,989 
worth  of  silver. 

Other  Occurrences.  —  Argentiferous  lead  ores  also  occur  in 
the  Ten  Mile  district  (8),  in  Chaffee  County,  and  along  the 
Eagle  River  (11).  They 
are  also  known  in  Red 
Mountain  (10  a),  and  in 
Rico  Mountain,  Dolores 
County  (4, 12, 13).  In  the 
last-mentioned  region  the 
mountains,  which  are 
the  remains  of  the  struc- 
tural dome  arising  above 
the  Dolores  plateau  lying 
in  the  San  Juan  region, 
contain  a  series  of  sedi- 
mentary beds  ranging 
from  Algonkian  to  Juras- 
sic in  agre,  which  have 


FIG.  86. — Diagrammatic  section  across  a 
northeasterly  lode  at  Rico,  Colo.,  showing 
"  blanket "  of  ore.  After  Ransome,  U.  S. 
Geol.  Surv.,  Z2d  Ann.  Rept.,  II. 


been   uplifted   partly  by 

the  intrusion  of  igneous 

rocks,  as  stocks,  sills,  and  dikes,  and  partly  by  upthrows  due 

to  faulting. 

The  ore  occurs  as  lodes,  replacements  in  limestone,  stocks, 
and  blankets,  the  last  consisting  usually  of  deposits  lying 
parallel  to  the  planes  of  bedding  or  to  the  sheets  of  igneous 
rock,  and  known  locally  as  "contacts,"  although  not  such 
in  the  true  sense. 

The  four  types  of  deposit  mentioned  may  pass  into  each 
other.  Most  of  the  ore  in  the  district  has,  however, 

2B 


370         ECONOMIC   GEOLOGY   OF   THE   UNITED   STATES 


come  from  the  blankets,  and  the  bulk  of  this  has  been 
found  in  the  Carboniferous,  especially  in  the  Hermosa 
formation,  a  striking  feature  of  the  deposits  being  their 
limited  vertical  range. 

The  ores  are  primarily  galena,  often  highty  argentifer- 
ous and  associated  with  rich  silver-bearing  minerals.      In 

many  deposits  the  more  or 
less  complete  oxidation  of 
the  silver  ores  has  resulted 
in  powdery  masses,  often 
very  rich  in  silver.  Below 
the  zone  of  oxidation,  the 
veins  have  not  been  success- 
fully worked. 

The  bulk  of  the  ores  can 
be  roughly  divided  into  py- 
ritic  ores,  usually  low  grade, 
and  silver-bearing  galena 
ores,  sometimes  containing 
rich  silver  minerals.  Quartz 
is  the  commonest  gangue 
mineral,  but  the  beautiful 
pink  rhodochrosite  is  also 
conspicuous. 

The  ore  deposition  is  be- 
lieved to  be  closely  associated  with  the  igneous  intrusions 
of  the  district,  especially  with  the  later  ones. 

Most  of  the  ore  produced  in  the  Rico  district  has  been 
shipped    crude    or    smelted    in    Rico    without    mechanical 
concentration. 
Park  City,    Utah  (2),   which  is  located  on  the  eastern 


FIG.  87.  — Vein  filling  a  fault  fissure, 
Enterprise  mine,  Rico,  Colo.  After 
Richard,  Amer.  Inst.  Min.  Eng., 
Trans.  XXVI:  927. 


SILVER-LEAD    ORES  371 

slope  of  the  Wasatch  range,  about  25  miles  southeast  of 
Salt  Lake  City,  has  made  Summit  County  famous  as  one 
of  the  important  mining  centers  of  this  country,  as  there 
are  here  large  bodies  of  rich  silver-lead  ores  carrying  minor 
values  of  gold  and  copper.  The  success  of  this  camp, 
therefore,  depends  more  or  less  on  the  condition  of  the 
silver  and  copper  industry. 

The  geological  section  involves  a  series  of  limestones, 
sandstones,  and  shales,  chiefly  of  Carboniferous  age,  and 
having  an  aggregate  thickness  of  over  6000  feet,  with  a 
general  dip  of  30  to  40  degrees  northwest,  and  traversed 
by  many  fissures,  faults,  and  intrusions,  the  last  being  of 
either  dioritic  or  porphyritic  types.  The  ores,  which  in 
the  oxidized  zone  are  cerussite,  anglesite,  azurite,  mala- 
chite, etc.,  and  in  the  sulphide  zone  are  galena,  tetrahe- 
drite,  and  pyrite,  occur  either  as  lodes  or  fissures,  or  as 
bedded  deposits  in  limestones.  The  latter,  which  supply 
most  of  the  ore,  form  replacements  in  certain  strata  of 
both  the  upper  Carboniferous  and  Permocarboniferous,  and 
lie  between  siliceous  members  as  walls.  Both  types  of  ore 
deposit  are  frequently  associated  with  porphyry. 

The  fissures  carry  either  silver  or  lead  with  or  without 
zinc,  and  copper  or  gold  with  some  silver.  The  replace- 
ment ores  of  the  limestones  hold  silver  and  lead  chiefly. 
The  contact  ores  contain  copper  and  gold  with  or  without 
silver,  and  form  irregular  bodies  in  metamorphic  limestone 
adjacent  to  the  igneous  rock.  The  ordinary  crude  ore 
carries  50  to  55  ounces  silver,  20  per  cent  lead,  .04  to  .05 
ounce  gold,  1.5  per  cent  copper,  10  to  18  per  cent  zinc. 
Silver  is  obtained  in  the  proportion  of  3  ounces  silver  to 
each  per  cent  iron,  1  ounce  silver  to  each  per  cent  lead, 


372          ECONOMIC   GEOLOGY   OF   THE   UNITED   STATES 

and  .5  ounce  silver  to  each  per  cent  zinc.  Bonanzas  are 
known.  The  low-grade  ores  are  treated  at  the  concen- 
trating mill,  while  the  rich  ores  are  shipped  to  the  smelter. 

Tintic  District,  Utah  (16).  —  This  district  lies  in  the  Tintic 
Mountains,  about  65  miles  southwest  of  Salt  Lake  City. 
The  ores  are  argentiferous  galena,  with  a  little  copper,  the 
average  per  ton  of  240,000  tons  being  silver,  52.44  oz.;  lead, 
270  Ibs.;  copper,  11.2  Ibs.;  gold,  .135  oz. 

The  section  of  nearly  14,000  feet  of  folded  Paleozoic 
sediments  includes  chiefly  limestones,  which  after  uplift 
and  erosion  were  covered  by  Tertiary  lavas  and  tuffs. 
The  ores  occur  in  zones  in  the  limestones,  as  fissures  in 
the  igneous  rocks,  and  along  the  contact.  The  minerals 
in  the  ore  bodies  are  quartz,  barite,  pyrite,  galena,  sphal- 
erite, enargite,  silver  and  gold  minerals  and  their  oxida- 
tion products. 

The  Tintic  is  one  of  the  oldest  camps  in  the  state,  the  ore 
having  been  discovered  in  1869,  and  it  was  at  first  shipped 
as  far  as  Baltimore  and  Wales.  Since  then  mills  have  been 
erected  at  the  mines.  The  chief  towns  are  Eureka,  Mam- 
moth, Robinson,  Silver  City,  and  Diamond. 

The  same  type  of  ore  occurs  in  Big  and  Little  Cottonwood 
canons  and  Bingham  Canon,  the  latter  having  been  worked 
longer  than  those  of  the  Tintic  district.  The  camps  lie 
southeast  and  southwest  of  Salt  Lake  City,  and  the  ores 
are  oxidized  lead-silver  ores,  parallel  to  the  bedding  of 
Carboniferous  limestones  and  the  underlying  quartzite. 
Galena  and  pyrite  occur  in  the  lower  workings  below 
water  level. 

Oceur  d'Alene,  Idaho  (14),  lying  in  the  northern  part  of 
the  state,  is  one  of  the  most  prominent  producers  in  the 


SILVER-LEAD   ORES 


373 


United  States,  having,  in  the  fifteen  years  preceding  1902, 
produced  about  $60,000,000  worth  of  lead  and  silver. 

The  formations  of  the  region  consist  of  slates,  sandstones, 
and  quartzites,  which  have  been  bent  into  east  and  west  folds, 
the  accompanying  metamor- 
phism  having  been  sufficient 
to  produce  new  minerals. 
Igneous  intrusions  are,  how- 
ever, rare.  The  ore  bodies, 
which  are  typical  veins,  con- 
taining argentiferous  galena, 
associated  with  much  siderite, 
occupy  fault  planes,  and  are 
oxidized  above.  The  chief 
minerals  are  quartz,  siderite, 
galena,  and  sphalerite.  The 
workable  deposits  carry  from  5  to  25  per  cent  lead,  the 
average  of  the  district  being  10  per  cent  and  7  ounces 
per  ton  silver. 

Montana  and  Nevada,  etc.  —  Montana  contains  several 
lead-silver  ore  localities.  Those  of  Neihart  (17)  occur  as 
veins  in  gneiss  and  igneous  rocks,  the  ores  being  galena, 
silver  sulphides,  and  some  blende.  The  veins  are  best  de-. 
fined  in  the  gneiss,  and  are  mostly  replacement  deposits, 
which  have  been  subsequently  fractured  and  secondarily 
enriched.  Lead-silver  ores  also  occur  at  Glendale  and  in 
Jefferson  County.  Some  are  also  known  in  South  Dakota 
and  New  Mexico  (3). 

The  Eureka  district  (10)  of  eastern  Nevada,  discovered  in 
1868,  is  chiefly  of  historic  importance.  The  ores  are  oxidized 
lead-silver  ores,  carrying  some  gold.  They  occur  in  Cambrian 


FIG.  88.  —  Section  of  lead-silver  vein, 
Coeur  d'Alene,  Ido.  (1)  Country 
rock.  (2)  Sheared  rock.  (3)  Galena 
and  siderite.  (4)  Fissure  with  fine- 
grained galena.  (5)  Barren ,  silicified 
country  rock.  After  Finlay,  Amer. 
Inst.  Min.  Engrs.,  Trans.  XXXIII : 
249. 


374         ECONOMIC  GEOLOGY  OF  THE  UNITED  STATES 

limestone  which  is  much  faulted  and  crushed,  and  is  part  of 
a  Paleozoic  section  30,000  feet  thick. 

The  ore  is  associated  with  a  great  fault,  and  is  oxidized  to 
a  depth  of  1000  feet.  There  are  two  mining  districts,  Pros- 
pect Hill  and  Ruby  Hill.  Near  the  mines  are  great  por- 
phyry masses  which  are  supposed  to  have  afforded  the  ores. 
Up  to  1882  the  output  was  not  far  from  160,000,000  of  pre- 
cious metals  and  225,000  tons  of  lead. 

REFERENCES  ON  LEAD-SILVER  ORES 

1.  Blow,  Amer.  Inst.  Min.  Engrs.,  Trans.  XVIII :  145,  1889.  2.  Boutwell, 
U.  S.  Geol.  Surv.,  Bull.  213  :  31, 1903 ;  225 :  141, 1904 ;  260 :  150,  1905. 
(Park  City,  Utah.)  3.  Clark,  Amer.  Inst.  Min.  Engrs.,  Trans.  XXIV : 
138.  (Lake  Valley,  New  Mex.)  4.  Cross  and  Spencer,  U.  S.  Geol. 
Surv.,  21st  Ann.  Kept.,  II:  15,  1900.  (Rico  Mts.,  Colo.)  5.  Curtis, 
U.  S.  Geol.  Surv.,  Mon.  VII,  1884.  (Eureka,  Nev.)  6.  Eldridge, 
U.  S.  Geol.  Surv.,  16th  Ann.  Kept.,  II :  217, 1895.  7.  Emmons,  U.  S. 
Geol.  Surv.,  Mon.  XII,  1886.  (Leadville,  Colo.  A  new  report  is  in 
preparation.)  8.  Emmons,  U.  S.  Geol.  Surv.,  Ten  Mile  Atlas  Folio. 
(Ten  Mile  district,  Colo.)  9.  Parish,  Colo.  Sci.  Soc.,  Proc.  IV :  151. 
(Rico.)  10.  Hague,  U.  S.  Geol.  Surv.,  Mon.  XX,  1892.  (Eureka, 
Nev.)  10  a.  Kedzie,  Amer.  Inst.  Min.  Engrs.,  Trans.  XVI:  570, 1888. 
(Red  Mt.)  11.  Olcott,  Eng.  and  Min.  Jour.  XLIII :  418,  436,  1887, 
and  LIII :  545,  1892.  (Eagle  Co.,  Colo.)  12.  Rickard,  Amer.  Inst. 
Min.  Engrs.,  Trans.  XXVI :  906, 1896.  (Enterprise  mine,  Rico,  Colo.) 

13.  Ransome,  U.  S.  Geol.  Surv.,  22d  Ann.  Rept.,  II:  229,  1901. 

14.  Ransome,   U.  S.  Geol.   Surv.,   Bull.   260:  274,   1905.       (Coaur 
d'Alene.)    15.  Spurr,  U.  S.  Geol.  Surv.,  Mon.  XXXI,  1898.    (Aspen, 
Colo.)      16.  Tower  and  Smith,  U.  S.  Geol.  Surv.,  19th  Ann.  Rept., 
Ill :  601,  1899.   (Tintic  district,  Utah.)   17.  Weed,  U.  S.  Geol.  Surv., 
20th  Ann.  Rept.,  Ill :  271,  1900. 


CHAPTER  XIX 
ALUMINUM 

Ores.  —  This  is  one  of  the  few  metals  whose  ores  do  not 
present  a  metallic  appearance.  Many  different  minerals  con- 
tain aluminum,  but  it  can  be  profitably  extracted  from  only 
a  few.  Common  clay,  for  example,  presents  an  inexhaustible 
supply,  but  the  chemical  combination  of  the  aluminum  in  it 
is  such  that  its  extraction  up  to  the  present  time  has  not  been 
found  practicable. 

The  ores  of  aluminum,  together  with  the  percentage  of 
the  metal  which  they  contain,  are :  corundum,  A12O3 
(53.3  per  cent);  cryolite,  A1F3,  3  NaF  (12.8  per  cent); 
bauxite,  A12O3,  2  H2O  (39.13  per  cent);  gillsite,  A12O3, 
3  H2O  (34.6  per  cent).  Of  these,  corundum  is  too  valuable 
as  an  abrasive,  and  is  not  found  in  sufficient  quantity  to 
permit  its  use  as  an  ore  of  aluminum.  Until  the  discovery 
of  bauxite,  cryolite  was  the  chief  source  of  the  metal,  all  of 
it  being  obtained  from  Greenland  (8). 

Bauxite  derives  its  name  from  Baux  in  southern  France, 
where  it  was  first  discovered,  but  in  recent  years  large  de- 
posits have  been  found  in  the  United  States.  It  is  usually 
pisolitic  in  structure,  and  may  sometimes  resemble  clay  in 
appearance.  The  common  impurities  are  silica,  iron  oxide, 
and  titanic  acid ;  and  the  variation  in  the  amount  of  these 
ingredients  can  be  seen  from  the  following  analyses  of  both 
domestic  and  foreign  occurrences :  — 
376 


376          ECONOMIC   GEOLOGY   OP  THE   UNITED   STATES 
ANALYSES  OF  BAUXITE 


1 

2 

3 

4 

5 

6 

Alumina  (A1208)  .  .  . 
Ferric  oxide  (Fe2O8)  .  . 
Silica  (SiOa)  
Lime  carbonate  (CaCO8)  .  . 
Titanic  acid  (TiOa)  .  .  . 
Water  (H2O)  

57.60 
25.30 
2.80 
.40 
3.10 
10.80 

61.89 
1.96 
6.01 

27.82 

63.16 
23.55 
4.15 

8.34 

59.22 
3.16 
3.30 

3.62 
28.80 
1  90 

61.00 
2.20 
2.10 

31.58 
3  12 

62.05 
1.66 
2.00 

30.31 
350 

Alkalies  (Na2O,  K2O)  .  .  . 

.79 

1.  Baux,  France.  2.  Glenravel,  Ireland.  3.  Wochein,  Germany. 
4.  Georgia.  5.  Rock  Run,  Alabama.  6.  Arkansas. 

Distribution  of  Bauxite  in  the  United  States.  —  Bauxite  in 
commercial  quantity  is  known  to  occur  in  but  three  districts 
in  the  United  States.  These  are  the  Georgia- Alabama  dis- 
trict, the  Arkansas  district,  and  a  small  area  in  southwestern 
New  Mexico.  The  New  Mexico  deposits  are  of  little  com- 
mercial importance  on  account  of  their  inaccessibility. 

G-eorgia- Alabama  (4,  6,  7).  — The  bauxite  deposits  of  these 
two  states  form  a  belt  about  60  miles  long  extending  from 
Jacksonville,  Alabama,  to  Cartersville,  Georgia.  The  ore, 
which  is  either  pisolitic  or  claylike  in  its  character,  forms 
pockets  or  lenses  of  variable  diameter  and  depth,  in  the  re- 
sidual clay  derived  from  the  Knox  dolomite.  A  pronounced 
feature  is  their  occurrence  close  to  900  feet  above  sea  level, 
few  being  found  above  950  feet  or  below  850  (4). 

The  bauxite  is  believed  by  Hayes  (4)  to  be  a  hot  spring 
deposit.  It  is  underlain  by  the  Knox  dolomite  and  this  in 
turn  by  the  Connasauga  shales  which  are  several  thousand 
feet  in  thickness,  and  contain  from  15  to  20  per  cent  of  alu- 
mina, and  also  pyrite.  The  region  is  one  of  marked  faulting. 


PLATE  XXV 


FIG.  1.  —  View  of  Bauxite  bauk,  Rock  Run,  Ala.    H.  Hies,  photo. 


FIG.  2.— Furnace  for  roasting  mercury  ore,  Terlingua,  Tex.    W.  H.  Turner,  photo. 


ALUMINUM 


377 


Alteration  of  the  pyrite  by  percolating  meteoric  waters  has 
yielded  sulphuric  acid,  which  attacked  the  alumina  of  the 
shale,  with  the  formation  of  alum  and  also  ferrous  sulphate. 
Both  of  these  have  been  carried  toward  the  surface  by  spring 
waters,  but  since  they  had  to  pass  through  the  higher  lying 


FIG.  89.  —  Geologic  map  of  Alabama-Georgia  bauxite  region.    After  Hayes, 
U.  S.  Geol.  Surv.,  16th  Ann.  Kept.,  Ill:  552. 

limestones,  the  lime  carbonate  acted  on  the  dissolved  alum 
according  to  the  following  equation : J  — 

A12(SO4)3  +  3  CaCO3  =  A12O3  +  3  CaSO4  +  3  CO2. 
The  alumina  thus  formed  was  a  light,  gelatinous  precipi- 
tate, which  was  carried  upward  into  spring  basins  on  the 
surface,  where  it  finally  settled.  The  pisolitic  structure  is 
thought  to  have  been  caused  by  the  balling  together  of  the 
gelatinous  mass  by  currents. 

1  For  clearness,  the  water  combined  with  the  alumina  is  left  out. 


378          ECONOMIC   GEOLOGY  OF   THE  UNITED   STATES 

The  Georgia- Alabama  deposits,  which  represent  a  unique 
type  of  occurrence,  were  discovered  in  1887,  and  have  been 
worked  steadily  since  that  time.  There  have  been  some  mis- 
givings regarding  the  exhaustibility  of  the  domestic  supply, 
but  the  discovery  and  development  of  the  next  described 
district  have  allayed  these  fears. 

Arkansas  (2,  3).  —  The  occurrence  of  bauxite  in  Arkansas 
has  been  known  since  1891,  but  owing  to  a  more  accessible 
eastern  supply,  there  was  little  development  in  that  region 
until  1900.  The  deposits,  which  are  much  more  extensive 
than  the  Georgia- Alabama  ones,  are  confined  to  a  small  area 


FIG.  90.  —  Section  of  Bauxite  deposit,  (a)  Residual  mantle ;  (6)  Red  sandy  clay 
soil;  (c)  Pisolitic  ore;  (d)  Bauxite  with  clay;  (e)  Clay  with  bauxite; 
(/)  Talus;  (g)  Mottled  clay;  (h)  Drainage  ditch.  After  Hayes. 

in  Pulaski  and  Saline  counties,  north  and  southwest  of  Little 
Rock.  They  have  an  average  thickness  of  10  to  15  feet  and 
show  two  distinct  types.  In  the  southwesterly  or  Bryant 
district  the  lower  beds  show  a  granitic  structure  and  rest 
directly  on  a  mass  of  kaolin  derived  from  the  elseolite- 
syenite,  and  it  is  probable  that  the  bauxite  has  also  been 
derived  directly  from  this  rock.  The  upper  beds  are  piso- 
litic  and  similar  in  character  to  the  Georgia- Alabama  ones. 
In  the  Fourche  Mountain  area  only  the  pisolitic  form  is 
found.  The  granitic  type  is  the  purest  and  corresponds  in 
composition  to  the  formula  of  gibbsite  rather  than  bauxite, 
while  the  white  bauxitic  kaolins  run  high  in  silica. 


ALUMINUM  379 

The  origin  of  the  Arkansas  bauxites  is  somewhat  obscure, 
but  Hayes  (3)  considers  that  subsequent  to  the  intrusion  of 
the  syenite  into  the  palaeozoics  of  that  region,  the  former 
was  exposed  by  erosion  of  the  latter.  This  was  followed  by 
a  submergence  of  the  surface  below  a  body  of  salt  or  highly 
alkaline  waters,  which  in  some  way  penetrated  the  still 
partially  hot  syenite,  and  dissolved  its  minerals.  On  re- 
turning to  the  surface  they  attacked  the  syenite  there, 
removing  silica  and  alkalies  and  depositing  alumina  in  its 
place.  Much  of  the  alumina  was  also  deposited  from  these 
waters  as  a  gelatinous  precipitate  on  the  ocean  bottom,  over 
the  syenite  surface.  Some  was  also  deposited  with  the 
Tertiary  sediments  then  forming. 

New  Mexico  (1).  — The  bauxite  deposits  which  occur  near 
Silver  City  appear  to  have  been  derived  from  a  basic  volcanic 
rock,  by  decomposition  and  alteration  in  place. 

Uses  of  Aluminum.  —  The  chief  use  of  this  metal  is  for 
making  wire  for  the  transmission  of  electric  currents,  but  a 
large  quantity  of  it  is  also  used  in  the  manufacture  of  articles 
for  domestic  or  culinary  use,  instruments,  boats,  and  other 
articles  where  lightness  is  wanted.  It  is  also  employed  in 
the  manufacture  of  special  alloys,  among  which  may  be  men- 
tioned magnalium,  an  alloy  of  aluminum  and  magnesium; 
and  wolframinium,  a  tungsten-aluminum  alloy.  One  alloy 
of  this  type  known  as  partinmm  is  said  to  have  a  ten- 
sile strength  of  over  49,000  pounds  per  square  inch;  Mc- 
Adamite,  an  alloy  of  aluminum,  zinc,  and  copper,  is  said 
to  possess  a  tensile  strength  exceeding  44,000  pounds  per 
square  inch ;  aluminum  silver  is  an  alloy  of  copper,  nickel, 
zinc,  and  aluminum;  aluminum  zinc  includes  a  series  of 


380 


ECONOMIC  GEOLOGY  OF  THE  UNITED  STATES 


alloys  containing  various  proportions  of  these  two  metals. 
Of  growing  importance  is  the  use  of  aluminum  for  litho- 
graphic work  as  a  substitute  for  stone  or  zinc.  Another 
extending  application  is  that  of  powdered  aluminum  for 
the  production  of  intense  heat  by  combustion,  and  in  this 
connection  it  is  used  for  welding  tramway  rails,  or  for  the 
reduction  of  rare  metals  from  their  oxides.  Aluminum  has 
also  been  tried  for  the  manufacture  of  grindstones  and  whet- 
stones, for  which  purpose  it  is  said  to  be  peculiarly  suited 
owing  to  the  property  it  has  for  forming  under  whetting 
action  a  very  fine  mass  which  adheres  strongly  to  steel.  A 
small  amount  of  aluminum  added  to  steel  prevents  air  holes 
and  cracks  in  casting. 

Uses  of  Bauxite.  —  Aside  from  being  used  for  the  manu- 
facture of  aluminum  and  alum,  bauxite  is  of  some  value 
for  the  manufacture  of  refractory  products,  its  heat-resisting 
qualities  being  very  great. 

Production  of  Bauxite.  —  The  production  of  bauxite  in  the 
United  States  has  been  as  follows :  — 

PRODUCTION  OF  BAUXITE  IN  THE  UNITED  STATES  FROM  1889  TO  1903 


YBAB 

GEORGIA 
LONG  TONS 

ALABAMA 
LUNG  TONS 

ARKANSAS 
LONG  TONS 

TOTAL 

VALUE 

1889.  .  .  . 
1890.  .  .  . 
1895.  .  .  . 
1899.  .  .  . 

1900.  .  .  . 
1902.  .  .  . 
1903.  .  .  . 

728 
1844 
3756 
15,736 

13,313 
14,499 

5045 

3445 
4645 
25,713 

728 
1844 
17,069 
35,280 

23,184 
27,322 
48,087 

$2366 
6012 
44,000 
125,598 

89,676 
120,366 
171,306 

19,739 
22,677 
22,374 

ALUMINUM 


381 


The  following  table   shows   the   annual   consumption   of 
bauxite  and  its  value  in  the  United  States :  — 

PRODUCTION,  IMPORTS,  EXPORTS,  AND  CONSUMPTION  OF  BAUXITE  IN 
THE  UNITED  STATES 


PRODUCTION 

IMPORTS 

EXPORTS 

CONSUMPTION 

YEAR 

Quan- 

Quan- 

Quan- 

Quan- 

tity 
Long 

Value 

tity 
Long 

Value 

tity 
Long 

Value 

tity 
Long 

Value 

Tons 

Tons 

Tons 

Tons 

1901 

18,905 

$79,914 

18,313 

167,107 

1,000 

$3,000 

36,218 

$144,021 

1902 

27,322 

120,366 

15,790 

54,410 

nil 

— 

43,112 

175,875 

1903 

48,087 

171,306 

14,684 

49,684 

nil 

— 

62,976 

220,990 

WORLD'S  PRODUCTION  OF  BAUXITE 


COUNTRY 

1900 

1901 

1902 

QUANTITY 
METRIC 
TONS 

VALUE 

QUANTITY 
METRIC 
TONS 

VALUB 

QUANTITY 
METRIC 
TONS 

VALUE 

United 
States     . 
France  .     . 
United 
Kingdom 

Total    . 

23,556 
58,530 

5,873 

$89,676 
92,596 

6,750 

19,207 
76,620 

10,357 

$79,914 
124,168 

14,515 

29,785 
96,900 

9,192 

$128,206 
174,685 

13,395 

87,959 

$189,022 

106,184 

$218,597 

135,877 

$316,286 

Prior  to  1890  nearly  all  the  bauxite  consumed  in  the 
United  States  was  imported  from  France.  The  French 
ore  has  a  high  iron  oxide  content,  and  very  little  is  now 
imported,  except  during  periods  of  low  ocean  freights. 
Most  of  it  is  purchased  by  Germany. 


382 


ECONOMIC   GEOLOGY   OF   THE   UNITED   STATES 


Most  of  the  bauxite  used  in  the  United  States  is  for 
the  manufacture  of  aluminum,  but  from  one  fourth  to  one 
half  of  the  total  is  employed  in  the  manufacture  of  chemi- 
cal salts  of  aluminum,  and  artificial  corundum,  known  as 
alundum.  The  Georgia-Alabama  bauxites,  on  account  of 
their  freedom  from  iron,  are  of  special  value  for  the  manu- 
facture of  alum.  In  Europe  much  is  used  as  a  refractory 
material  for  lining  furnaces. 

The  production  of  aluminum  in  the  United  States  since 
1883  has  been  as  follows  :  — 

PRODUCTION  OF  ALUMINUM  IN  THE  UNITED  STATES 


YEAR 

QUANTITY 
POUNDS 

YEAR 

QUANTITY 
POUNDS 

1883      .... 

83 

1900  

7  150  000 

1885 

283 

1901 

7  150  000 

1890      .... 

61281 

1902  

7  300  000 

1895 

920  000 

1903 

7  500  000 

The  domestic  output  comes  from  four  large  plants. 
WORLD'S  PRODUCTION  OF  ALUMINUM 


IS 

01 

1] 

)02 

COUUTBY 

QUANTITY 
METRIC 
TONS 

VALUE 

QUANTITY 
METRIC 
TONS 

VALUE 

United  States     .     .     . 

3,244 
1  200 

$2,238,000 
560  000 

3,311 
1  355 

$2,284,900 
638  830 

United  Kingdom    .     . 
Switzerland    .... 

560 
2,500 

1,225,000 

600 
2,500 

1,201,425 

Total       .... 

7,504 

7,766 

MANGANESE  383 


REFERENCES  ON  ALUMINUM  AND  BAUXITE 

Blake,  Arner.  Inst,  Min.  Engrs.,  Trans.  XXIV :  571, 1895.  (N.  Mex.) 
2.  Branner,  Jour.  Geol.,  V :  263,  1897.  (Ark.)  3.  Hayes,  U.  S. 
Geol.  Surv.,  21st  Ann.  Kept.,  Ill :  435,  1901.  (Ark.)  4.  Hayes, 
U.  S.  Geol.  Surv.,  16th  Ann.  Kept.,  Ill:  547,  1895.  (Ga.-Ala.) 
,5.  Laur,  Amer.  Inst.  Min.  Engrs.,  Trans.  XXIV  :  234,  1895.  (The 
bauxites.)  6.  Watson,  Amer.  Geol.,  XXVIII:  25,  1901.  (Ga.) 
7.  Watson,  Ga.  Geol.  Surv.,  Bull.  11,  1904.  (Ga.)  8.  For  cryolite, 
see  Min.  Indus.,  VI :  251,  1897. 


MANGANESE 

Ores.  —  While  many  different  minerals  contain  this  metal, 
practically  the  only  ones  of  commercial  value  are  the  oxides 
and  carbonates,  and  in  this  country  only  the  former.  The 
silicates  are  not  used  as  a  source  of  manganese,  owing  to  their 
high  silica  percentage. 

The  important  ores  of  manganese  are  the  following :  pyro- 
lusite,  the  black  oxide  (MnO2;  63.2  per  cent  Mn) ;  psilome- 
lane  (chiefly  MnO2,  H2O  ;  K  and  Ba  variable),  one  of  the 
most  abundant  manganese  ores ;  braunite  (Mn2O3;  69.68  per 
cent  Mn)  ;  and  wad,  a  low-grade,  earthy  brown  or  black  ore, 
with  the  percentage  of  manganese  varying  from  15  to  40  per 
cent.  Wad  is  often  of  too  low  grade,  due  to  impurities, 
to  be  used  as  an  ore  of  manganese ;  but  it  is  sometimes  em- 
ployed for  paint.  Rhodochrosite  (MnCO3),  though  found  as 
a  common  gangue  mineral  in  some  western  mines,  does  not 
serve  as  a  source  of  manganese. 

The  several  ores  of  manganese  are  often  intimately  as- 
sociated, the  pyrolusite  generally  assuming  a  crystalline  and 
the  psilomelane  a  massive  character.  Manganese  oxides  are 
also  often  intermixed  with  more  or  less  oxide  of  iron,  and 
considerable  amounts  of  the  metal  are  obtained  from  man- 


384          ECONOMIC   GEOLOGY   OF   THE  UNITED   STATES 

ganiferous  zinc,  silver,  or  iron  ores.  Since  much  manga- 
nese is  used  in  iron  reduction,  the  last  association  is  of 
importance. 

To  be  of  commercial  value  a  manganese  ore  should  have 
at  least  40  per  cent  metallic  manganese,  and  should  be  low 
in  phosphorus  and  silica.  High-grade  ores  run  from  50  to 
60  per  cent  manganese. 

The  price  of  manganese  ores  in  1903  was  $8.97  per  long 
ton;  of  manganiferous  iron  ore,  $2.69  (18-32  per  cent  Mn) 
and  $2.40  (1-10  per  cent  Mn)  ;  of  manganiferous  silver  ores, 
$3.63. 

Origin.  —  Manganese  oxide  deposits  are  usually  of  second- 
ary origin,  having  been  formed  by  weathering  processes, 
which  caused  the  decay  of  the  parent  rock  containing  man- 
ganiferous silicates,  and  the  change  of  these  latter  to  oxides. 
By  circulating  ground  water  they  have  often  been  concen- 
trated in  residual  clays.  Although  iron  also  may  have  been 
present  in  the  parent  rock,  and  the  two  are  sometimes  de- 
posited together,  still  they  have  in  many  instances  been 
separated  from  each  other,  due  to  the  fact  that  conditions 
favorable  for  precipitation  are  not  the  same  for  both  (4), 
or  because  the  soluble  compounds  of  manganese  formed  by 
weathering  are  sometimes  more  stable  than  corresponding 
iron  compounds,  and  hence  may  be  carried  farther  by  cir- 
culating waters  before  they  are  deposited. 

Distribution  of  Manganese  Ores  in  the  United  States.— 

Although  manganese  ores  are  widely  distributed  in  the 
United  States,  only  a  few  localities  are  of  commercial  im- 
portance. This  is  partly  owing  to  the  uncertainty  of  the 
extent  of  the  ore  deposits  and  partly  to  the  high  percentage 


MANGANESE 


385 


of  phosphorus  which  many  of  the  ores  contain,  together  with 
their  remoteness  from  lines  of  transportation. 

Eastern  Area.  —  Manganese  deposits  are  found  in  the  At- 
lantic States  from  Vermont  to  Alabama,  and  two  states  in 
this  belt,  Georgia 
and  Virginia,  lead 
in  the  domestic 
production.  The 
common  mode  of 
occurrence  in  this 
district  is  as  nod- 
ules or  lumps  in 
residual  clay,  simi- 
lar to  the  limonites 
of  the  same  area. 
In  Virginia,  at 
Crimora,  Augusta 
County  (2),  the  ore 

forms  pockets  5  to  6  feet  thick  and  20  to  30  feet  long  in  a 
bed  of  clay  276  feet  thick. 

In  northern  Georgia  (1,  3,  7)  the  ore  results  from  the 
decay  of  limestone  and  shales,  Cave  Spring  and  Carters- 
ville  being  important  localities.  The  deposits  are  found 
in  the  areas  underlain  by  both  the  crystalline  and  Paleozoic 
rocks,  but  only  those  associated  with  the  latter  have  proven 
to  be  of  commercial  importance.  In  this  region  the  rocks 
consist  of  Cambro-Silurian  limestones  and  quartzites,  which 
have  been  much  folded  and  faulted,  and  have  then  weath- 
ered down  to  a  residual  clay,  which  is  often  not  less  than 
100  feet  thick.  The  ore  occurs  as  pockets,  lenticular  masses, 
stringers,  grains,  or  lumps,  irregularly  scattered  through  the 

2c 


FIG.  91.  — Map  showing  Georgia  manganese  areas. 
After  Watson,  Amer.  Inst.  Min.  Engrs.,  Trans. 
XXXIV:  209. 


386 


ECONOMIC   GEOLOGY   OF   THE   UNITED   STATES 


clay  and  rarely  forming  distinct  beds.  None  of  the  de- 
posits are  large,  though  some  30  feet  in  length  have  been 
worked.  More  or  less  limonite,  barite,  ocher,  and  bauxite 
may  be  associated  with  the  ore,  and,  indeed,  complete  gra- 
dations from  manganese  to  iron  ore  are  found,  as  shown 
by  the  following  analyses  :  — 


Mn  

60.61 

54.94 

41.98 

15.26 

2.30 

Fe  

1.45 

3.62 

16.22 

39.25 

52  02 

p 

052 

.034 

007 

193 

04 

The  better-grade  ores  are  usually  low  in  silica,  iron,  and 
phosphorus.     In  the  Cartersville  district,  which  is  the  more 


FIG.  92.  —  Section  in  Georgia  manganese  area,  showing  geologic  relations  of 
manganese,  limonite,  and  ocher.  After  Watson,  Amer.  Inst.  Min.  Engrs., 
Trans.  XXXIV:  219. 

important,  the  ore  is  found  in  residual  clays  derived  from 
the  Beaver  limestone  and  Weisner  quartzite,  while  in  the 
Cave  Spring  area  it  occurs  only  in  the  clays  overlying  the 
Knox  dolomite. 

Penrose  (5)  thought  that  the  manganese  was  derived  from 
the  underlying  Cambro-Silurian  sediments,  while  Watson 
on  the  contrary  believes  that  the  crystalline  rocks  to  the 
east  and  south  have  furnished  the  ore,  as  none  is  found  in 
the  parent  rock  from  which  the  clays  were  derived.  The 
manganese  was  probably  taken  into  solution  as  a  sulphate 
and  concentrated  by  circulating  waters  of  meteoric  origin 
in  the  residual  clays  where  now  found. 


MANGANESE 


387 


The  Georgia  (7)  deposits  have  been  worked  for  a  num- 
ber of  years,  and  the  manganese  was  formerly  marketed 
chiefly  in  England ;  but  the  output  is  now  sold  entirely  in 
the  United  States.  The  ore,  which  has  to  be  purified  by 
washing  and  crushing,  is  used  in  part  for  paint  and  in 
part  for  steel  manufacture. 

Arkansas.  —  Manganese  ore  is  found  in  the  region  around 
Batesville  (5,  6),  associated  with  horizontally  stratified  lime- 
stones and  shales,  ranging  from  Ordovician  to  Carbonifer- 
ous age  (Fig.  93).  The  Cason  shale,  of  Silurian  age, 
occurring  near  the  middle  of  the  section  (Fig.  93  £),  carries 


FIG.  93.  —  Section  in  Batesville,  Ark.,  manganese  region,  illustrating  geological 
structure  and  relation  of  different  formations  to  marketable  and  non-market- 
able ore.  After  Van  Ingen,  Sch.  of  M.  Quart.,  XXII:  324. 

manganese  nodules  high  in  phosphorus,  which  are  not 
marketable,  and  others  are  found  in  the  pits  of  residual 
clay  derived  from  it.  Farther  down  the  slopes  marketable 
ore  (Fig.  93  c),  which  has  been  derived  by  leaching  of  the 
first-mentioned  ore,  is  found  occurring  in  residual  pockets 
in  the  lower  lying  limestones,  while  the  residual  clays 
(Fig.  93  a),  formed  at  a  higher  level  than  the  Cason  shale, 
are  barren  of  manganese. 

Other  United  States  Occurrences.  —  California  has  a  num- 
ber of  manganese  deposits,  of  which  some  are  reported  to 
be  of  high  quality  (8)  ;  they  have  been  used  largely  in 


388          ECONOMIC   GEOLOGY   OF   THE   UNITED   STATES 

chlorination  works  for  the  reduction  of  gold  ores.  Man- 
ganese occurs  in  Triassic  sandstones  near  Thompson,  Utah, 
and  the  locality  became  a  producer  in  1901  (8).  Much 
manganiferous  iron  ore  and  manganiferous  silver  ore  is 
annually  obtained  from  the  Leadville  district  of  Colorado, 
the  former  being  used  by  steel  works  in  making  spiegel- 
eisen  and  the  latter  as  a  flux  in  smelters.  Lake  Superior 
iron  ores  at  times  carry  manganese,  but  it  usually  does 
not  exceed  1  per  cent. 

Uses  of  Manganese.  —  One  of  the  principal  uses  of  man- 
ganese is  in  the  manufacture  of  alloys.  Of  these,  spiegel- 
eisen,  an  alloy  of  iron  and  manganese  with  under  20  per 
cent  manganese,  and  ferromanganese,  a  similar  alloy  with 
over  20  per  cent  manganese,  are  important.  Other  alloys 
are  manganese  bronze,  manganese  and  copper  with  or 
without  iron;  silver  bronze,  an  alloy  of  manganese,  alu- 
minum, zinc,  copper,  and  silver;  and  manganese-titanium 
alloys. 

Manganese  is  also  used  as  an  oxidizing  agent  in  the 
manufacture  of  chlorine,  bromine,  and  disinfectants ;  as  a 
coloring  agent  in  calico  printing  and  dyeing,  in  the  making 
of  glass,  pottery,  brick,  as  well  as  in  paints.  It  is  also 
employed  as  a  decolorizer  in  green  glass. 

Production  of  Manganese.  —  Although  much  used  in  mak- 
ing glass  and  steel,  of  which  latter  material  the  United 
States  is  the  largest  manufacturer  in  the  world,  neverthe- 
less the  domestic  production  is  small.  This  consequently 
necessitates  the  importation  of  large  quantities,  which  are 
obtained  chiefly  from  Brazil. 


MANGANESE 


PRODUCTION  AND  VALUE  OF  MANGANESE  ORES  IN  THE  UNITED 
STATES  (IN  LONG  TONS) 


YEAR 

PRODUCTION 

VALUE 

1880 

5761 

f  86  415 

1885         

23,258 

190,281 

1890 

25684 

219  050 

1895    

9,547 

71,769 

1900 

11  771 

100  289 

1901  

11,995 

116,722 

1902 

7477 

60911 

1903  

2,825 

25,335 

PRODUCTION    AND    VALUE    OF   MANGANESE   ORES   IN    THE   UNITED 
STATES  BY  STATES  (IN  LONG  TONS) 


STATE 

1901 

1902 

1903 

PRODUC- 
TION 

VALUE 

PRODUC- 
TION 

VALUE 

PRODUC- 
TION 

VALUE 

Arkansas     .    .    . 
Georgia  .... 
Utah  
Virginia  .... 
All  others   .     .     . 
Total     .    .    . 

91 
4,074 
2,500 
4,275 
1,055 

$657 
24,674 
31,250 
52,853 
7,288 

82 
3,500 

3,041 

824 

$422 
20,830 

29,444 
10,215 

500 
483 
1,801 
41 

$2,930 
2,415 
19,611 
379 

11,995 

$116,722 

7,477 

$60,911 

2,825 

$25,335 

PRODUCTION  AND  VALUE  OF  DIFFERENT  KINDS  OF  MANGANESE  ORES 
IN  THE  UNITED  STATES  (IN  LONG  TONS) 


1901 

1902 

1903 

KIND  OF  ORE 

PRODUC- 
TION 

VALUE 

PRODUC- 
TION 

VALUE 

PRODUC- 
TION 

VALUE 

Manganese  ores   . 

11,995 

$116,722 

7,477 

$60,911 

2,825 

$25,335 

Manganiferous 

iron  ores  .    .    . 

574,489 

1,475,084 

901,214 

2,001,626 

584,493 

1,571,750 

Manganiferous 

silver  ores    .     . 

228,187 

865,959 

194,132 

908,098 

179,205 

649,727 

Manganiferous 

zinc  residuum  l 

52,311 

52,311 

65,246 

65,246 

73,264 

73,264 

Total     .     .     . 

866,982 

$2,510,076 

1,168,069 

$3,035,881 

839,787 

$2,320,076 

1  As  this  is  a  by-product  in  the  treatment  of  zinc  ores,  the  value  given 
to  it  is  nominal. 


390          ECONOMIC   GEOLOGY   OF   THE   UNITED   STATES 

The  imports  of  manganese  ore  in  1903  amounted  to 
146,056  long  tons,  valued  at  $1,278,108,  and  came  chiefly 
from  Brazil,  but  the  British  East  Indies,  Cuba,  Germany, 
and  Russia  also  supplied  some. 

REFERENCES  ON  MANGANESE 

1.  Brewer,  Ala.  Ind.  and  Sci.  Soc.  Proc.,  VI :  72.  (Ga.)  2.  Hall,  Amer. 
Inst.  Min.  Engrs.,  Trans.  XX  :  46,  1892.  (Crimora,  Va.)  3.  Hayes, 
Amer.  Inst.  Min.  Engrs.,  Trans.  XXX  :  403,  1901.  (Ga.)  4.  Pen- 
rose,  Jour.  Geol.,  1 :  275,  1893.  (Chemical  relations  of  iron  and 
manganese  in  sedimentary  rocks.)  5.  Penrose,  Ark.  Geol.  Surv., 
Kept,  for  1890,  Vol.  I,  1891.  (Uses,  ores,  and  deposits.)  6.  Van 
Ingen,  Sch.  of  M.  Quart.,  XXII  :  318,  1901.  (Batesville,  Ark.) 
7.  Watson,  Amer.  Inst.  Min.  Engrs.,  Trans.  XXXIV:  207,  1904. 
(Ga.)  8.  Birkenbine,  Mineral  Census,  1902,  Mines  and  Quarries. 

MERCURY 

Ores.  —  While  mercury  is  sometimes  found  native  in  the 
form  of  quicksilver,  the  most  common  ore  is  cinnabar  (HgS), 
which  contains  86.2  per  cent  mercury.  Native  amalgam 
of  mercury  and  silver  is  known,  and  calomel,  the  chloride, 
as  well  as  other  compounds,  are  sometimes  found. 

Mode  of  Occurrence.  —  Mercury  ores  are  not  confined  to 
any  particular  formation,  but  are  found  in  rocks  ranging 
from  the  Ordovician  to  Recent  Age  in  different  parts  of 
the  world.  Nor  are  they  peculiar  to  any  special  type  of 
rock,  although  igneous  rocks  are  often  found  in  the  vicinity 
of  them.  They  occur  as  veins,  disseminations,  or  as  masses 
of  irregular  form.  Silica,  either  crystalline  or  opaline,  and 
calcite  are  common  gangue  minerals,  while  pyrite  or  mar- 
casite  are  rarely  wanting,  and  bitumen  is  widespread. 

Distribution  in  the  United  States.  —  California  has  always 
been  the  most  important,  and,  in  fact,  at  times,  the  only 


MERCURY 


391 


producing   state.      Deposits   are,   however,  also   known   in 
Texas,  Oregon,  Utah,  Nevada,  and  New  Mexico. 

California  (1,2,7). — The  California  ores  occur  chiefly 
in  metamorphosed  Cretaceous  or  Jurassic  rocks,  with  some 
in  the  Miocene  and  even 
Quaternary.  The  depos- 
its, which  are  termed 
"  chambered  veins  "  by 
Becker,  are  fissured  zones. 
Eruptive  rocks  seem  in 
many  cases  to  be  involved 
in  the  ore  formation,  and 
at  New  Almaden  a  rhyo- 
lite  dike  runs  parallel  with 
the  ore  body.  The  ore 
here  occurs  along  the  con- 
tact between  serpentine 
and  shale,  filling  in  part 
the  interstices  of  a  brec- 
cia. These  mines,  which  are  the  largest  in  the  state,  have 
been  worked  to  a  depth  of  over  2500  feet. 

Other  occurrences  are  in  Colusa  County,  where  the  cin- 
nabar is  found  in  altered  serpentine,  and  in  Napa  County, 
where  it  occurs  along  the  contact  of  sandstone  and  slate. 
The  minerals  associated  with  these  are  bitumen,  free  sul- 
phur, stibnite,  mispickel,  gold  and  silver,  chalcopyrite,  py- 
rite,  millerite,  quartz,  calcite,  barite,  and  borax.  At  New 
Idria  the  ore  is  the  same,  but  the  wall  rock  is  metamor- 
phic  sandstones  and  shales.  A  third  important  mine  is 
the  Sulphur  Bank,  which  is  of  very  recent  date.  The 
vein  is  a  fissure  filled  with  brecciated  fragments,  and  cuts 


FIG.  94.  —  Map  of  California  mercury  local- 
ities. 


392 


ECONOMIC  GEOLOGY  OF  THE  UNITED  STATES 


through  sandstone,  shale,  and  augite  andesite,  the  cinnabar 
cementing  the  breccia  together,  but  at  times  also  impreg- 
nating the  walls.  Hot  waters  which  circulate  through  the 
vein  still  deposit  gelatinous  silica. 

At  Steamboat  Springs  the  waters  carry  gold,  sulphide 
of  arsenic,  antimony,  and  mercury,  sulphides  or  sulphates 
of  silver,  lead,  copper,  zinc,  iron  oxide,  and  possibly  other 
metals.  They  also  contain  sodium  carbonate,  sodium  chlo- 
ride, sulphur,  and  borax. 

Cinnabar  is  known  in  Lane  and  Douglas  counties,  Oregon. 

Texas    (3,  4,  5). — The    Terlingua    district    of    Brewster 

County,  Texas,  has  caused  much  interest  in  recent  years. 

The  ore  bodies  thus  far  known  lie  in  a  belt  15  miles  east 

and  west  by  4  miles 
wide,  with  Fresno 
Canon  on  the  west- 
ern boundary,  but 
the  remoteness  from 
the  railroad  (90 
miles)  and  the  lack 
of  water  form  seri- 
ous obstacles  to  the 
rapid  development 
of  this  district.  The 
rocks  are  Cretaceous 
limestone,  which 
have  been  broken  by 
several  large  northwest-southeast  faults,  with  minor  parallel 
ones  between.  Overlying  these  are  younger  sediments  and 
volcanics.  Only  one  of  the  ore  bodies  is  close  to  an  intru- 
sive contact. 


FIG.  95.  —  Map  showing  Texas   mercury  region. 
After  Hill,  Eng.  and  Min.  Jour.,  LXXIV:  305. 


MEBCURY  393 

Cinnabar  is  the  commonest  ore,  but  other  mercury  min- 
erals are  present,  including  quicksilver,  which  is  usually 
intimately  associated  with  calcite.  Hematite  and  limonite 
are  very  common  accessories, 
but  pyrite  is  rare.  The  ore  is 
most  frequently  found  in  fis- 
sure veins  with  calcite  gangue, 
these  fissures  forming  two 
series  at  right  angles  to  each 

Other,  of  which  the  northeast-  FIG.  96.  — Section  of  cinnabar  vein  in 

limestone,  Terlingua,  Tex.  After 

SOUthwest  ones  are  productive.  Phillips,  Univ.  Tex.  Min.  Surv., 

Still  4  *  32 

The  ore  also  occurs  in  brec- 

ciated  strips,  or  as  lateral  extension  veins.  The  workings 
are  all  shallow.  Recently  an  extension  of  this  area  has  been 
found  in  the  Chisos  Mountains  near  Terlingua. 

Origin.  —  The  origin  of  mercury  ores  has  been  studied 
chiefly  by  Becker  (1)  and  later  by  Schrauf  (6).  The  for- 
mer points  out  that  silica  (either  crystalline  or  amorphous) 
and  calcite  are  common  gangue  minerals,  but  pyrite  or 
marcasite  are  almost  equally  abundant,  as  is  also  bitumen. 
In  addition  to  these,  the  ores  show  an  irregular  association 
with  other  metallic  minerals,  such  as  antimony,  silver,  lead, 
copper,  arsenic,  zinc,  or  even  gold.  Becker  believes  that 
the  cinnabar  has  been  precipitated  from  ascending  waters 
by  bituminous  matter,  having  come  up  in  solution  as  a 
double  sulphide  with  alkaline  sulphides.  He  further  sug- 
gests that  the  deposits  represent  impregnations  and  are 
not  replacements. 

Uses  of  Mercury.  —  The  most  important  use  of  quick- 
silver is  in  the  extraction  of  gold  and  silver  by  the  process 


394 


ECONOMIC   GEOLOGY   OF  THE   UNITED   STATES 


of  amalgamation  (see  Gold  and  Silver).  Its  power  of  form- 
ing amalgams  with  other  metals  makes  it  of  value  in  the 
arts  for  the  preparation  of  a  substance  used  for  silver- 
ing mirrors  and  for  other  purposes.  Because  it  is  liquid 
at  ordinary  temperatures  it  can  be  employed  in  the  manufac- 
ture of  thermometers ;  and  this  fact,  added  to  its  weight, 
renders  it  of  special  value  in  the  construction  of  mercurial 
barometers.  In  medicine  mercury  is  used  in  various  forms, 
chiefly  as  calomel,  while  cinnabar  and  other  compounds  of 
mercury  are  valuable  in  the  manufacture  of  pigments.  For 
this  purpose  it  was  used  by  the  American  Indians  and  by 
the  other  early  races  of  people. 

Extraction.  —  The  mercury  is  usually  obtained  from  the 
ore  by  the  simple  process  of  sublimation,  the  cinnabar 
being  heated  in  furnaces,  and  the  fumes  of  sulphur  and 
metallic  mercury  allowed  to  pass  off.  The  latter  are 
caught  in  condensing  chambers,  while  the  former  escape 
into  the  air. 

Production  of  Mercury.  —  California  was  for  many  years 
practically  the  only  domestic  source  of  mercury,  but  in 
1898  Texas  became  a  producer,  and  will  no  doubt  con- 
tinue so.  The  output  of  mercury  is  quoted  in  flasks  of 
76£  pounds  net.  That  of  California  since  1850  has  been 
as  follows :  — 

PRODUCTION  OF  MERCURY  IN  CALIFORNIA  FROM  1850  TO  1900 
(Flasks  of  76£  pounds) 


1850 7,723 

1860 10,000 

1870 30,077 


1880 59,926 

1890 22,926 

1900 26,317 


MERCURY 


395 


PRODUCTION  OF  MERCURY  IN  CALIFORNIA  AND  TEXAS  FROM 
1901  TO  1903 


1901 

1902 

1903 

QUANTITY 
FLASKS 

VALUB 

QUANTITY 
FLASKS 

VALUE 

QUANTITY 

FLASKS 

VALU* 

Texas  .     . 

2,932 

$132,438 

5,319 

$239,350 

5,029 

$211,218 

California 

26,720 

1,285,014 

28,974 

1,228,498 

30,526 

1,330,916 

The  imports  of  mercury  in  1903  were  valued  at  $1065, 
and  the  exports  at  $446,845. 

The  world's  production  for  1902  was  as  follows:  — 


COUNTRY 

QUANTITY 
METRIC  TONS 

VALTTM 

United  States 

1  190 

$1  467  848 

511 

568,929 

Italy  

260 

310,080 

1425 

1,941,387 

REFERENCES  ON  MERCURY 

1.  Becker,  Geology  of  Quicksilver  Deposits  of  Pacific  Slope,  U.  S.  Geol. 
Surv.,  Mon.  XIII,  1888.  2.  Becker,  U.  S.  Geol.  Surv.,  Min.  Res., 
1892:  139,  1893.  (Origin.)  3.  Blake,  W.  P.,  Amer.  Inst.  Min. 
Engrs.,  Trans.  XXV  :  68, 1896.  (Cinnabar  in  Texas.)  4.  Hill,  Eng. 
and  Min.  Jour.,  LXXIV :  305, 1902.  (Tex.)  5.  Phillips,  Univ.  Tex. 
Min.  Surv.,  Bull.  4,  1902.  (Terlingua  district,  Texas.)  6.  Schrauf, 
Zeitsch.  prak.  Geologic,  II :  10,  1894.  (Origin.)  7.  Watts,  W.  L., 
Cal.  State  Min.  Bur.,  XI :  239, 1893.  (Lake  County,  California.) 


CHAPTER  XX 
ANTIMONY 

Ores.  —  Stibnite  (Sb2S3)  is  the  most  important  ore  of 
antimony,  and  the  metal  is  rarely  obtained  from  any  other 
mineral,  although  native  antimony  has  been  sparingly 
found.  The  oxide  senarmontite  (Sb2O3)  seldom  occurs  in 
any  quantity.  A  small  amount  of  antimony  is  present  in 
some  silver-lead  ores.  The  stibnite,  together  with  a  gangue 
of  quartz,  and  sometimes  calcite,  usually  forms  veins  cutting 
igneous,  sedimentary,  or  metamorphic  rocks. 

Distribution  of  Antimony  in  United  States.  —  Antimony 
has  been  found  at  a  number  of  localities  in  the  Cordilleran 
region,  but  the  great  distance  of  the  deposits  from  the  rail- 
road, together  with  the  fact  that  the  smelting  plants  are 
located  in  the  East,  make  them  of  little  commercial  value, 
and  no  domestic  production  has  been  reported  since  1901. 
Moreover,  the  large  output  of  antimony  ores  and  metal 
abroad,  combined  with  low  ocean  freights  and  the  absence 
of  any  import  tax  on  crude  antimony,  are  of  themselves 
discouraging  to  domestic  competition. 

The  large  amount  of  antimony  now  manufactured  in 
the  United  States  is  obtained  :  (1)  as  a  by-product  from 
the  smelting  of  foreign  and  domestic  lead-silver  ores  con- 
taining small  quantities  of  antimony ;  (2)  antimony  regu- 
lus,  or  metal  from  foreign  countries ;  (3)  foreign  ore. 
306 


ANTIMONY 


397 


Uses.  —  Antimony  metal  is  used  chiefly  in  the  manufac- 
ture of  alloys  of  lead,  tin,  zinc,  etc.  Type  metal,  which  is 
an  alloy  of  lead,  antimony,  and  bismuth,  has  the  property 
of  expanding  at  the  moment  of  solidification.  Britannia 
metal  is  tin  with  10  to  16  per  cent  antimony  and  3  per 
cent  copper.  Babbitt,  or  antifriction,  metal  consists  of 
antimony  and  tin,  with  small  amounts  of  lead,  copper,  bis- 
muth, zinc,  and  nickel.  Tartar  emetic,  a  potassium-anti- 
mony tartrate,  is  used  in  medicine  and  as  a  mordant  for 
dyeing,  while  antimony  persulphide  is  employed  for  vulcan- 
izing and  coloring  rubber. 

Production  of  Antimony.  —  The  production  of  metallic 
antimony  from  domestio  and  foreign  ores  since  1890  was 
as  follows :  — 

PRODUCTION  OF  ANTIMONY  FROM  DOMESTIC  AND  FOREIGN  ORES 


YEAR 

QUANTITY 
SHORT  TONS 

VALUE 

YEAR 

QUANTITY 
SHORT  TONS 

VALUE 

1890 

938 

$175,508 

1901 

2639 

8539,902 

1895 

2013 

304,169 

1902 

3561 

634,506 

1900 

4226 

837,896 

1903 

3128 

548,433 

The  production  in  1903  was  about  three  fifths  of  the 
entire  consumption.  The  hard  lead  (antimonial  lead) 
produced  in  the  United  States  in  1903,  as  a  by-product 
from  impure  lead-silver  ores,  was  21,237,440  pounds,  con- 
taining 24  per  cent  antimony. 

REFERENCES  ON  ANTIMONY 

1.  Blake,  U.  S.  Geol.  Surv.,  Min.  Res.,  1883-4 :  641, 1885.  2.  Comstock, 
Ark.  Geol.  Surv.,  Ann.  Kept,  for  1888,  I:  136.  (Ark.)  3.  Min. 
Indus.,  2:  13,1894.  (General.) 


398          ECONOMIC   GEOLOGY   OF   THE   UNITED  STATES 

ARSENIC 

Although  arsenic-bearing  minerals  are  widely  distributed 
in  many  countries,  the  commercially  valuable  occurrences 
are  few. 

Arsenopyrite  (FeAsS),  called  also  mispickel  and  arsenical 
pyrites,  is  the  main  source  of  the  metal.  Realgar  (As2S2) 
and  orpiment  (As2S8)  may  also  serve  as  ores. 

Arsenopyrite  is  mined  in  Washington,  where  the  mineral 
is  used  for  making  arsenious  oxide,  and  more  recently  de- 
posits have  been  opened  up  in  Floyd  and  Montgomery 
counties,  Virginia.  At  the  former  locality  the  ore,  which 
is  chiefly  arsenopyrite,  averages  about  14  per  cent  arsenic, 
.7  ounce  gold,  and  3  ounces  silver  per  ton  (2). 

Arsenopyrite  is  used  chiefly  for  the  manufacture  of  arse- 
nious oxide.  It  is  employed  in  medicine,  as  a  pigment,  and 
as  an  alloy  with  lead  for  making  shot.  Arsenious  oxide  is 
used  for  making  paris  green,  in  glassware  for  destroying 
the  iron  coloration,  in  certain  enamels,  and  as  a  fixing  and 
conveying  substance  for  aniline  dyes. 

The  domestic  production  of  arsenious  oxide  in  1903 
amounted  to  611  short  tons  valued  at  $36,691,  and  was  all 
made  at  Everett,  Wash.  This,  however,  supplied  only  one 
quarter  of  the  domestic  demand,  and  large  quantities  were 
imported  from  Canada,  Germany,  and  Spain.  The  imports 
of  arsenic  and  its  compounds  in  1903  amounted  to  8,357,661 
pounds,  valued  at  $294,602. 

REFERENCES  ON  ARSENIC 

1.  Min.  Indus.,  n :  25, 1894.  2.  Strnthers,  U.  S.  Geol.  Surv.,  Min.  Res., 
1903 :  321,  1904.  (General.)  3.  Merrill,  Non-Metallic  Minerals, 
30, 1904. 


CHROMIC   IKON   OEE  399 

BISMUTH 

Ores.  —  The  principal  ores  of  this  metal,  together  with 
the  percentage  of  metallic  bismuth  which  they  contain,  are : 
Bismuthinite  (Bi2S3,  81.2)  ;  biwnite  (Bi2O3,  96.6)  ;  and  bis- 
mutite  (Bi2O3,  CO2,  H2O,  80.6).  Although  all  of  these 
contain  a  high  percentage  of  metallic  bismuth,  the  content 
of  the  ore  as  mined  does  not  usually  exceed  ten  or  fifteen 
per  cent.  Bismuth  ores  are  commonly  associated  with  those 
of  gold  and  silver,  and  the  metal  is  obtained  as  a  by-product 
in  the  smelting  of  these. 

Distribution.  —  There  are  many  scattered  occurrences  of 
bismuth  ores  throughout  the  Rocky  Mountain  states,  but 
Colorado  is  the  most  important,  and  in  1904  Leadville  was 
the  only  producing  region. 

Uses  and  Production.  —  Bismuth  is  chiefly  valuable  on 
account  of  the  easily  fusible  alloys  which  it  forms  with  lead, 
tin,  and  cadmium  ;  the  melting  point  of  some  of  these  lies 
between  64°  C.  and  94.5°  C.  They  are  therefore  employed 
in  safety  fuses  for  electrical  apparatus,  safety  plugs  for 
boilers,  dental  amalgams,  etc.  The  production  of  bismuth 
in  1904  was  5184  pounds,  valued  at  $314.  The  imports  of 
metallic  bismuth  in  1904  amounted  to  185,905  pounds, 
valued  at  $339,058. 

CHROMIC  IRON  ORE 

Ores.  —  Chromite  (FeO,  Cr2O3)  is  the  chief  source  of  the 
compounds  of  the  metal  chromium  which  are  used  in  the  arts. 
This  ore  occurs  sometimes  in  alluvial  deposits,  but  more 
commonly  in  basic  magnesian  rocks,  notably  serpentine. 


400 


ECONOMIC   GEOLOGY  OF   THE  UNITED   STATES 


Origin  of  Chromite.  —  It  has  been  pointed  out  by  Pratt  (4) 
that  chromite  occurs  most  commonly  around  the  border  of 
basic  magnesian  rocks  of  igneous  origin.  This  is  believed 
to  indicate  that  the  chromium  existed  in  the  original  molten 
rock,  and  that,  as  this  basic  magma  cooled,  the  chromite, 
being  one  of  the  earliest  minerals  to  crystallize,  separated 
out  along  the  border  of  the  mass  because  this  portion  was 
the  first  to  cool.  As  the  cooling  proceeded,  convection  cur- 
rents within  the  molten  mass  would  bring  additional  supplies 
to  the  border. 

Analyses  (5).  — The  following  table  gives  the  composition 
of  several  of  the  types  of  chromic  iron  ores  :  — 


COLERAINE, 

FRANCE 

CAN. 

Concentrated 

ASIA 
MINOR 

STYRIA 

CALIF. 

RUSSIA 

Product 

Cr203 

37.00 

53.64 

53.00 

53.00 

42.20 

59.00 

SiO2 

2.53 

2.31 

2.15 

2.50 

5.48 

2.20 

A1203 

13.15 

14.02 

7.62 

8.00 

13.60 

10.00 

MgO 

12.53 

15.75 

12.31 

11.58 

14.88 

11.62 

FeO 

34.79 

11.47 

24.92 

24.92 

23.84 

18.18 

CaO 

2.81 

The  price  of  chromic  iron  ore  is  based  on  its  percentage  of  chromic 
oxide,  the  standard  ore  containing  50  per  cent.  Every  unit  above  this 
is  valued  at  from  75  cents  to  $1  per  ton ;  but  when  the  percentage  is 
below  50  per  cent,  the  value  decreases  at  an  even  greater  rate.  How- 
ever, ores  carrying  only  45  per  cent  of  chromic  oxide  are  easily  market- 
able. Low  silica  is  desirable. 

Distribution  in  the  United  States.  —  In  the  United  States 
chromite  was  for  a  time  obtained  from  Chester  and  Delaware 
counties,  Pennsylvania,  and  Baltimore  County,  Maryland, 


CHKOMIC   IRON   ORE  401 

and  the  exhaustion  of  these  deposits  was  followed  by  the 
opening  of  others  in  San  Luis  Obispo  County,  California. 
Subsequently  the  importation  of  Turkish  and  Russian  chro- 
mite  commenced,  followed  by  additional  supplies  from 
Canada  and  Newfoundland.  This  foreign  chrome  iron  ore, 
especially  the  Turkish,  can  be  placed  on  the  American 
market  so  cheaply  that  there  has  been  little  development  of 
our  own  deposits.  The  importation  of  chromic  iron  ore 
from  New  Caledonia  is  also  increasing. 

Chromite  occurs  in  a  number  of  places  in  California  besides  the  one 
referred  to  above ;  and  also  in  North  Carolina,  in  a  belt  of  peridotite  rock 
extending  from  Ashe  County  to  Clay  County.  In  this  area,  however,  the 
chromite  has  been  found  in  quantity  at  only  a  few  localities  (3). 

Uses.  —  Metallic  chromium  has  no  direct  use;  but  raw 
chromite  and  chromium  salts  have  a  variety  of  applications. 
Owing  to  its  great  heat-resisting  qualities,  chromite  is 
employed  in  the  manufacture  of  refractory  bricks.  Such 
bricks  are  sometimes  used  for  lining  basic  open-hearth  fur- 
naces, and  as  a  hearth  lining  for  water-jacket  furnaces  in 
copper  smelting.  They  stand  rapid  changes  of  temperature 
well,  and  are  not  attacked  by  molten  metals. 

In  the  presence  of  carbon,  chromium  makes  steel  extremely 
hard  and  resistant  to  shocks ;  therefore  chrome  steel  is 
suited  to  a  variety  of  uses,  as  in  the  manufacture  of  plates, 
hard-edged  tools,  etc.  An  alloy  of  iron  and  chromium  is 
used  in  armor  plates,  alloys  of  ferro-chromium  and  ferro- 
nickel  being  added  to  the  molten  steel  before  casting.  Most 
of  the  chromite  mined  is  used  for  pigments  because  of  the 
red,  yellow,  and  green  color  of  its  compounds,  chromate  and 
bichromate  of  potash.  In  these  forms  the  substance  is  em- 


402 


ECONOMIC   GEOLOGY   OF   THE  UNITED   STATES 


ployed  in  dyeing,  calico  printing,  and  the  making  of  pig- 
ments useful  in  painting,  printing  wall  papers,  and  coloring 
pottery.  Alkaline  bichromates  are  employed  for  tanning 
skins,  and  some  chromium  salts  have  a  medicinal  value. 


Production  of  Chromite.  —  The  amount  of  chromite  pro- 
duced in  the  United  States  is  small,  and  in  1903  California 
was  the  only  source  of  supply.  The  production  for  several 
years  was  as  follows :  — 

PRODUCTION  OF  CHROMITE  m  THE  UNITED  STATES  FROM  1900  TO  1903 


YEAR 

QUANTITY 
LONG  TONS 

VALUE 

1900 

140 

$1400 

1901  

368 

5790 

1902  

315 

4567 

1903  

150 

2250 

The  value  of  the  imports  for  the  last  three  years  was :  — 


YEAR 

CHBOMATE  AND 
BICHROMATE 
OF  POTASH 

CHROMIC 
ACID 

CHROME 
ORB 

TOTAL 

1901     

129,224 

$10,861 

$363,108 

$403,193 

1902     

11,115 

582,597 

593,712 

1903 

3°  174 

292  025 

324  199 

REFERENCES  ON  CHROMIC  IRON  ORE 

1.  Glenn,  Amer.  Inst.  of  Min.  Engrs.,  Trans.  XXXI :  374, 1902.  2.  May- 
nard,  ibid.,  XXVII :  283,  1898.  (Newfoundland.)  3.  Pratt,  U.  S. 
Geol.  Surv.,  Mineral  Resources,  1901 :  941,  1902.  (General.) 
4.  Pratt,  N.  Ca.  Geol.  Surv.,  1 :  269,  1905.  (Origin.)  5.  Anon., 
Min.  Indus.,  VI :  147,  1898.  (Analyses.) 


NICKEL  AND   COBALT  403 

MOLYBDENUM 

Ores  and  Occurrences.  —  Molybdenite  (MoS2)  and,  less  com- 
monly, wulfenite  (PbMoO4),  are  the  chief  sources  of  this 
metal. 

Molybdenite  forms  irregular  masses  or  disseminations  in 
crystalline  rocks,  and  many  occurrences  are  known  in  the 
West,  for  example,  in  California,  Washington,  Montana,  Utah, 
Arizona,  New  Mexico,  and  in  the  East,  in  Maine.  An  ore  to 
be  marketable  must  contain  over  45  per  cent  of  molybdenum 
and  be  free  from  copper,  the  average  price  of  a  50  to  55  per 
cent  ore  being  about  $400  per  ton. 

Uses.  —  Its  chief  use  is  in  the  manufacture  of  chemicals, 
especially  ammonium  molybdate,  and  for  coloring  porcelain 
green.  A  nick  el -molybdenum  alloy  is  also  made.  The  use 
of  molybdenum  for  hardening  steel  is  increasing,  it  being 
used  chiefly  for  tool  steel. 

Production  of  Molybdenum.  —  The  production  of  molyb- 
denite in  1903  was  6200  tons  crude  ore,  but  very  little  of 
this  was  concentrated  and  marketed. 

REFERENCES  ON  MOLYBDENUM 

1.  Crooks,  Bull.  Geol.  Soc.  Amer.,  XV:  283,  1904.  (N.Y.)  2.  Pratt, 
U.  S.  Geol.  Surv.,  Min.  Res.,  1903 :  307, 1904.  (General.)  3.  Smith, 
U.  S.  Geol.  Surv.,  Bull.  260 :  197,  1905.  (E.  Me.) 

NICKEL  AND  COBALT 

Ores.  —  These  two  metals  can  best  be  treated  together,  for 
nearly  all  the  ores  containing  one  are  apt  to  carry  some  of  the 
other,  and  furthermore,  in  smelting,  the  two  metals  go  into 
the  same  matte,  and  are  separated  later  in  the  refining  process. 


404 


ECONOMIC   GEOLOGY   OF   THE   UNITED   STATES 


The  ores  of  nickel  and  cobalt,  together  with  their  composi- 
tion and  the  percentage  of  nickel  or  cobalt  they  contain,  are : 


ORE 

COMPOSITION 

Ni 

Co 

Pyrrhotite  (nickeliferous) 
Millerite 

FenS12 

NiS 

0-6 
646 

— 

Pentlandite   

(FeNi)S 

22 

Genthite 

2  NiO    2  MgO  3  SiO    6  H  O 

2246 

NiAs 

43  9 

(CoND  S 

30  53 

21  34 

The  nickeliferous  pyrrhotite  is  the  most  widely  distributed 
of  the  nickel  ores,  and  may  carry  small  amounts  of  cobalt. 
It  is  also  called  magnetic  pyrites.  The  percentage  of  nickel 
ranges  from  a  trace  to  6  per  cent,  but  an  increase  above  this 
brings  it  into  pentlandite.  The  millerite  is  sometimes  found 
associated  with  pyrrhotite  ores.  Of  the  genthite,  the  variety 
known  as  garnierite  forms  the  ores,  and  carries  from  21  to  45 
per  cent  nickel  oxide. 

Distribution.  —  Very  little  direct  mining  for  nickel  and 
cobalt  is  done  in  the  United  States,  but  at  Mine  la  Motte, 
Missouri,  considerable  quantities  have  been  obtained  annually 
as  a  by-product  in  lead  mining.  (See  under  Lead.) 

Eastern  Occurrences  of  Nickel.  —  The  Gap  Nickel  Mine, 
Lancaster  County,  Pennsylvania,  is  the  most  important 
eastern  occurrence.  It  was  actively  worked  from  1863  to 
1880,  being  during  that  period  the  only  nickel  ore  mined 
on  this  continent.  In  1902  the  mine  was  again  operated. 
The  ore  is  pyrrhotite  associated  with  amphibolite,  an  altered 
intrusive,  the  whole  inclosed  by  mica-schist.  The  pyrrhotite 
is  believed  to  have  originated  by  magmatic  segregation  (4). 


NICKEL   AND  COBALT  405 

Nickel  minerals  have  also  been  found  in  the  basic  magnesian 
rocks  of  North  Carolina. 

Western  Occurrences. — Deposits  of  nickel  and  cobalt  ores  are 
known  in  Idaho  and  Oregon,  but  they  have  not  yet  assumed 
importance.  Nickel  ore  is  found  in  Ferry  County,  Wash- 
ington, and  other  deposits  are  reported  from  Sheridan  and 
Piney  Creek,  Wyoming,  as  well  as  at  several  localities  in 
Nevada,  Idaho,  Arizona,  and  South  Dakota ;  but  none  of  the 
occurrences  are  worked,  and  the  main  source  of  supply  on 
this  continent  comes  from  Sudbury,  Ontario  (1,  2). 

There,  the  ore,  which  occurs  in  enormous  masses,  is  a  nickeliferous 
pyrrhotite,  and  the  output  forms  probably  one  half  of  the  world's  produc- 
tion. The  ore  occurs  on  the  contact  of  quartzite  and  diorite,  or  forms, 
more  often,  scattered  irregular  masses  in  the  latter.  Its  origin  has  been 
a  matter  of  some  dispute,  some  having  regarded  it  as  a  product  of  mag- 
matic  segregation,  while  others  believe  the  ore  to  have  been  deposited  in 
the  crushed  diorite.  A  partial  analysis  shows :  Cu,  8.05 ;  Ni,  2.97 ;  Fe, 
26.21 ;  SiOa,  26.05 ;  S,  19.08. 

The  second  important  source  of  the  world's  nickel  ore  is  the  mines  of 
New  Caledonia,  in  the  Pacific  Ocean,  off  the  east  coast  of  Australia.  The 
ore  is  garnierite. 

Uses  of  Nickel.  —  The  most  important  and  increasing  use  of 
nickel  is  for  the  manufacture  of  nickel  and  nickel-chromium 
steel.  This,  on  account  of  its  great  hardness,  strength,  and 
elasticity,  is  used  for  making  armor  plate,  gun  shields,  turrets, 
ammunition  hoists,  etc.  Krupp  steel,  which  may  be  taken 
as  a  type,  has  approximately  3.5  per  cent  nickel,  1.5  per  cent 
chromium,  and  .25  per  cent  carbon.  Owing  to  its  abrasive 
resistance,  nickel-steel  is  now  much  used  for  rails.  Other 
important  uses  are  for  large  forgings,  marine  engines,  wire 
cables,  and  electrical  apparatus.  A  steel  with  25  to  30  per 
cent  nickel  shows  high  resistance  to  corrosion  by  salt,  fresh 


406 


ECONOMIC  GEOLOGY  OF  THE  UNITED  STATES 


or  acid  waters,  or  by  superheated  steam.     German  silver  is 
an  alloy  of  zinc,  copper,  and  nickel. 

Uses  of  Cobalt.  —  Cobalt  steel,  while  having  a  high  elastic 
limit  and  breaking  strength,  cannot  compete  with  nickel  steel 
on  account  of  its  high  cost,  and  the  main  use  for  cobalt  is  as 
a  pigment. 

Production. — The  production  of  nickel  from  domestic  ores 
and  cobalt  oxide  in  the  United  States  from  1892  to  1901  was : 

PRODUCTION  OF  NICKEL  AND  COBALT  FROM  DOMESTIC  ORES 


YEAR 

NICKEL 

COBALT  OXIDE 

Quantity 
Pounds 

Value 

Quantity 
Pounds 

1892      

92,252 
10,302 
9,715 
6,700 

5,748 
114,200 

$50,739 
3,091 
3.8B6 
3,551 
2,701 
45,900 

7,869 
14,458 
6,471 
13,360 
3,730 
120,000 

1895 

1900      

1901 

1902           

1903 

The  amount  of  nickel  produced  in  Canada  in  1903  was 
12,505,510  pounds.  The  imports  of  cobalt  oxide  in  1903  were 
73,350  pounds,  valued  at  $  145,264,  while  the  total  value  of 
the  nickel  imported  in  the  same  year  was  $1,849,620.  The 
exports  of  nickel  oxide  and  matte  in  1901  were  $1,483,889. 

THE  WORLD'S  PRODUCTION  OF  NICKEL 


QUANTITY 

VALUE 

Canada,  1903  

12  505  510  pounds 

$5,002,204 

France  1902            .... 

1  600  met  tons 

1  080  800 

Germany,  1902    

1,605  met.  tons 

1,122,271 

PLATINUM  GROUP  OF  METALS  407 

REFERENCES  ON  NICKEL  AND  COBALT 

1.  Barlow,  Can.  Geol.  Surv.,  Ann.  Kept.,  XIV,  pt.  H,  1904.  (Ontario.) 
2.  Dickson,  Amer.  Inst.  Min.  Engrs.,  Trans.  XXXIV:  3,  1904. 
(Ontario.)  3.  Hodges,  Amer.  Inst.  Min.  Engrs.,  Trans.  XIII :  657, 
1885.  (Nev.)  4.  Kemp,  Amer.  Inst.  Mm.  Engrs.,  Trans.  XXIV : 
620,  1895.  (Pa.)  5.  Neill,  Amer.  Inst.  Min.  Engrs.,  Trans.  XIH : 
634,  1885.  (Mo.) 

PLATINUM  GROUP  OF  METALS 

Platinum.  —  The  ores  of  platinum  are  native  platinum 
(100  per  cent  Pt),  and  sperrylite,  PtAS2  (56.5  per  cent 
Pt).  The  former  is  commonly  found  in  placer  deposits,  but 
it  has  also  been  noted  in  basic  igneous  rocks  rich  in  olivine, 
such  as  peridotite,  or  in  serpentine  derived  from  it.  The 
sperrylite  never  occurs  in  large  quantities,  but  has  been 
found  in  association  with  nickel  and  copper  ores.  Iridos- 
mine  and  osmiridiuni  are  also  known  to  carry  platinum. 

The  nuggets  found  in  placers  are  commonly  regarded  as 
being  pure  native  platinum,  but  this,  according  to  Kemp  (4), 
is  only  true  in  part,  most  of  those  assayed  yielding  between 
70  and  85  per  cent,  and  the  richest  recorded  being  86.5  per 
cent.  The  balance  is  made  up  largely  of  iron,  the  highest 
percentage  of  this  noted  being  19.5  per  cent  in  a  Ural 
specimen.  Iridium,  rhodium,  and  palladium  are  always 
present.  Until  the  platinum  falls  below  60  per  cent  the 
iridium  rarely  reaches  5  per  cent,  rhodium  4  per  cent,  while 
palladium  is  less  than  2  per  cent.  Other  elements  that  have 
been  detected  in  the  nuggets  are  osmium,  ruthenium,  cop- 
per, and  even  gold,  while  chromite  is  a  common  associated 
mineral  (4). 

Distribution  in  the  United  States.  —  The  domestic  supply 
of  platinum,  never  large,  has  been  obtained  in  recent  years 


408 


ECONOMIC   GEOLOGY   OF   THE  UNITED   STATES 


as  a  secondary  product  from  gold-placer  deposits  in  Trinity 
and  Shasta  counties,  California,  and  while  its  occurrence  has 
been  reported  in  many  other  gold  placers  of  the  Northwest 
and  Alaska,  still  none  of  them  have  proven  sufficiently  rich 
to  work.  Iridosmine  and  a  natural  alloy  of  iron  and  nickel 
called  josephinite  are  found  associated  with  the  gold. 

In  addition  to  the  above  sources,  platinum  is  also  found  in 
the  copper  ores  of  the  Rambler  mine,  Wyoming,  and  has 
been  saved  from  the  slimes  obtained  in  treating  the  copper 
ore  and  matte  at  this  locality.  The  covellite  in  the  ore 
assays  .06  to  1.4  ounces  per  ton  of  platinum. 

Uses.  —  Platinum  was  first  used  as  an  adulterant  of  gold, 
and  in  Russia  it  was  used  for  coinage  from  1828  to  1845. 
At  the  present  time  it  is  employed  for  crucibles  and  other 
chemical  apparatus  which  are  to  be  subjected  to  high  temper- 
atures or  strong  acids.  It  is  also  of  value  in  dentistry,  for 
electric  lamps  and  electric  apparatus,  for  jewelry,  and  in 
photography.  The  price  of  it  has  risen  steadily  in  recent 
years,  so  that  it  is  as  valuable  as  gold. 

Production.  —  The  production  in  the  United  States  from 
1880  to  1903  was  as  follows :  — 

PRODUCTION  OF  PLATINUM  IN  THE  UNITED  STATES 


YEAR 

QUANTITY 

OUNCES 

VALUE 

YEAR 

QUANTITY 
OUNCES 

VALUE 

1880 

100 

$400 

1900 

400 

$2,500 

1885 

250 

187 

1901 

1,408 

27,526 

1890 

600 

2,500 

1902 

94 

1,874 

1895 

150 

900 

1903 



6,080 

PLATINUM   GROUP   OF  METALS  409 

Since  the  close  of  1899  platinum  has  risen  steadily  in  price, 
reaching  a  maximum  of  $20  per  ounce  in  1902. 

The  imports  of  platinum,  both  crude  and  manufactured, 
amounted  to  $1,987,980  in  1902,  and  $2,055,933  in  1903. 
The  domestic  production  is  entirely  inadequate  to  supply 
the  demand,  and  the  greater  portion  of  the  supply  of  the 
United  States,  and  in  fact  the  world,  is  obtained  from  the 
platinum  placers  of  the  Urals  (5). 

REFERENCES  ON  PLATINUM 

1.  Day,  U.  S.  Geol.  Surv.,  19th  Ann.  Kept.,  VI :  265,  1898.  2.  Day,  Amer. 
Inst.  Min.  Engrs.,  Trans.  XXX  :  702, 1901.  (N.  Amer.)  3.  Donald, 
Eng.  and  Min.  Jour.,  LV :  81,  1893.  (Can.)  4.  Kemp,  Min.  Indus., 
X :  540,  1902 ;  and  U.  S.  Geol.  Surv.,  Bull.  193,  1902.  (General.) 
5.  Purington,  Eng.  and  Min.  Jour.,  LXXVII :  720,  1904.  (Russia.) 

Palladium.  —  This  metal  is  found  associated  with  platinum 
and  also  native  and  alloyed  with  gold  (Brazil).  It  is  of 
silver-white  color,  ductile  and  malleable,  and  is  unaffected 
by  the  air.  Its  great  rarity  and  consequent  high  value  has 
restricted  its  use,  but  a  small  amount  is  used  for  some  mathe- 
matical and  surgical  instruments,  for  compensating  balance 
wheels  and  hair  springs  for  watches,  and  for  finely  graduated 
scales. 

In  the  United  States  it  has  been  reported  from  the  platinum 
deposits  of  the  Pacific  Coast  and  from  the  Rambler  mine  in 
Wyoming. 

Osmium.  —  This,  the  heaviest  and  most  infusible  metal 
known,  occurs  alloyed  with  platinum  and  also  with  iridium 
in  iridosmine.  In  the  United  States  small  quantities  have 
been  found  in  the  platinum  placers  of  California. 

Iridosmine  is  employed  for  pointing  pens  and  fine  tools, 


410          ECONOMIC   GEOLOGY   OF  THE   UNITED   STATES 

while  osmic  acid  is  used  for  staining  anatomical  prepara- 
tions in  microscopic  work. 

Iridium.  —  Iridium  is  found  chiefly  in  Russia  and  Cali- 
fornia, alloyed  with  platinum  or  osmium.  It  is  a  lustrous, 
steel-white  metal  of  great  hardness,  and  is,  next  to  osmium, 
the  most  refractory  metal  known. 

An  alloy  of  iridium  and  platinum  has  been  used  for 
standard  weights  and  measures,  and  iridium  is  also  used 
in  photography. 

TIN 

Ores.  —  Cassiterite  (SnO2),  with  78.6  per  cent  metallic  tin, 
is  the  principal  ore  of  this  metal,  but  owing  to  the  pres- 
ence of  impurities  the  ore  rarely  shows  this  composition. 
Its  hardness  (6-7),  imperfect  cleavage,  nonmagnetic  charac- 
ter, high  specific  gravity  (6.8-7.1),  and  brittleness  help  to 
distinguish  it  from  other  minerals  that  are  liable  to  occur 
with  it.  The  mineral  stannite*  or  tin  pyrites,  a  complex 
sulphide  of  copper,  iron,  and  tin,  rarely  serves  as  an  ore. 
Stream  tin  is  the  name  applied  to  cassiterite  found  in 
placers. 

Mode  of  Occurrence.  —  Cassiterite  of  primary  character  is 
usually  found  in  veins  of  pegmatite,  or,  more  commonly, 
greisen  (quartz  and  muscovite  or  lepidolite),  around  the 
edges  of  granite  areas.  This,  together  with  the  associa- 
tion of  fluorite,  tourmaline,  and  topaz  with  the  ore,  indicate 
quite  clearly  that  it  may  be  the  result  of  fumarolic  action. 
This  type  of  occurrence  is,  however,  of  little  commercial 
value,  and  over  80  per  cent  of  the  world's  supply  comes 
from  placers  whose  materials  have  been  derived  from  tin- 
bearing  veins. 


TIN 


411 


Distribution  in  the  United  States.  —  Although  tin  has 
been  found  at  a  number  of  localities  in  the  United  States, 
only  a  very  few  of  these  can  be  looked  upon  as  commercial 
sources. 

The  Black  Hills  (1,2,6)  of  South  Dakota  and  Wyoming 
is  perhaps  the  best  known  tin-producing  region  of  the 
United  States, 
and  although 
much  money  has 
been  sunk  in 
its  development 
and  many  ex- 
citing rumors 
have  been  pub- 
lished regarding 
it,  the  output 
has  been  ex- 
ceedingly small. 
Here  the  tin  oc- 
curs either  in 
pegmatite  dikes 
or  quartz  veins  and  in  placers.  The  Harney  Peak  deposits 
of  the  northern  Black  Hills  have  produced  but  little,  but 
the  Nigger  Hill  region  of  Wyoming,  in  the  northwestern 
part  of  the  hills,  seems  to  be  more  promising. 

More  recently  the  tin  deposits  of  North  and  South  Caro- 
lina (4, 6)  have  been  attracting  considerable  attention.  These 
lie  in  a  belt  extending  from  Cherokee  County,  South  Caro- 
lina, to  Lincoln  County,  North  Carolina.  The  cassiterite 
occurs  as  an  original  constituent  of  pegmatite  dikes,  but 
is  somewhat  irregularly  distributed  in  them.  Some  of  the 


FIG.  97.  —  Sketch  map  showing  location  of  Carolina  tin 
belt.    After  Graton,  U.  S.  Geol.  Sura.,  Bull.  260. 


412          ECONOMIC   GEOLOGY   OF  THE   UNITED   STATES 

mines  now  being  worked  at  Gaffney,  South  Carolina,  and 
Kings  Mountain,  North  Carolina,  are  promising.  An  inter- 
esting feature  is  that  the  dikes  are  of  undoubted  igneous 
origin. 

Tin  has  been  reported  from  a  number  of  localities  in 
Alaska  (3),  but  the  production  is  still  very  small,  that 
during  1903  and  1904  having  amounted  to  not  more  than 
100  tons. 

The  most  important  occurrences  are  on  the  Seward  pen- 
insula, where  it  occurs  in  placers,  quartz-porphyry  dikes, 
granites,  or  in  sedimentaries  near  their  contact  with  the 
igneous  rock.  In  the  dikes  the  accompanying  minerals  are 
tourmaline,  topaz,  fluorite,  zinnwaldite,  wolframite,  quartz, 
epidote,  pyrite,  galena,  etc. 

The  amount  of  tin  ore  produced  in  the  United  States 
is  entirely  too  small  to  supply  the  demand,  and  the  main 
source  of  supply  for  this  country,  and  indeed  for  the  world, 
is  the  Malay  peninsula,  while  other  regions  of  commercial 
importance  are  Australia,  Bolivia,  and  Great  Britain. 

Uses  of  Tin.  —  Tin  is  used  chiefly  for  the  manufacture  of 
bronze  and  tin  plate,  and  to  a  smaller  extent  in  plumbing 
as  well  as  less  important  purposes.  Britannia  metal  is  com- 
posed of  from  82  to  90  parts  of  tin  alloyed  with  antimony, 
copper,  and  sometimes  zinc. 

Production  of  Tin.  —  The  world's  production  for  a  number 
of  years  has  been  behind  the  demand,  a  fact  which  has  not 
only  kept  up  the  price  of  this  metal,  but  also  stimulated 
prospecting  and  mining. 

The  world's  production  for  1904  as  given  by  the  Engineer- 
ing and  Mining  Journal  was  :  — 


TITANIUM  413 

COUNTRY  TONS 

Straits  Settlements 65,696 

Banka  and  Billiton 16,394 

Bolivia 10,304 

Australia  and  Tasmania 5,692 

England 4,796 

Germany  and  Austria 112 

Miscellaneous 140 

Total       103,134 

The  price  of  tin  on  the  New  York  market  in  1904  averaged 
about  28  cents  per  pound.  The  United  States  in  1904  con- 
sumed about  43,120  tons  of  tin. 

REFERENCES  ON  TIN 

1.  Blake,  Amer.  Inst.  Min.  Engrs.,  Trans.  XIII:  691.  (Black  Hills.) 
2.  Blake,  U.  S.  Geol.  Surv.,  Min.  Res.,  1883-84 :  592,  1885.  (Ores 
and  deposits).  3.  Collier,  U.  S.  Geol.  Surv.,  Bull.  225,  1904. 
(Alaska  and  general.)  4.  Graton,  U.  S.  Geol.  Surv.,  Bull.  260  :  188, 
1905.  (N.  Ca.  and  S.  Ca.)  5.  Hess  and  Graton,  U.  S.  Geol.  Surv., 
Bull.  260  :  161,  1905.  (Occurrence  and  distribution).  6.  Struthers 
and  Pratt,  U.  S.  Geol.  Surv.,  Min.  Res.,  1903 :  335,  1904.  (U.  S.) 
7.  Weed,  U.  S.  Geol.  Surv.,  Bull.  178,  1901.  (Texas.)  Also 
Bull.  213 :  99,  1903.  8.  Winslow,  Eng.  and  Min.  Jour.,  XL :  320, 
1885.  (Va.) 

TITANIUM 

Ores.  —  Among  the  minerals  carrying  titanium  the  most 
abundant  is  ilmenite  (FeO,  TiO2),  which  occurs  in  many 
deposits  of  magnetite.  Rutile  (TiO2,  60  per  cent  Ti  when 
pure),  though  less  abundant,  is  not  uncommon.  Titanium  is 
also  found  in  a  number  of  other  minerals,  many  of  which 


Occurrence.  —  For  many  years  Norway  has  been  the  chief 
producer  of  this  metal ;  but  in  1900  large  deposits  of  rutile 
were  discovered  in  Virginia,  from  which,  up  to  the  end  of 
1901,  about  40,000  pounds  had  been  extracted. 


414          ECONOMIC   GEOLOGY   OF   THE   UNITED   STATES 

The  Virginia  ore  (2),  which  is  found  in  Nelson  County, 
occurs  in  the  form  of  small  granules,  disseminated  through 
a  ground  mass  of  feldspar  or  as  a  segregation  in  quartz,  in  a 
rock  of  probable  igneous  origin.  Until  the  discovery  of  the 
Virginia  deposits,  the  domestic  demand,  which  has  been 
small,  was  supplied  from  deposits  in  Chester  County, 
Pennsylvania. 

Uses.  —  Titanium  is  used  for  producing  yellow  underglaze 
colors  on  pottery,  and  also  in  the  manufacture  of  artificial 
teeth,  to  give  them  an  ivory  tint.  Another  use  is  in  the 
alloy  ferro-titanium.  Its  commercial  values  as  a  steel-hard- 
ening metal  are  not  yet  thoroughly  proven,  but  from  .5  to  3 
per  cent  titanium  appear  to  materially  increase  the  transverse 
and  tensile  strength  of  steel.  By  the  use  of  the  electric  fur- 
nace, ferro-titanium  can  be  produced  directly  from  the  ores, 
which  would  open  a  use  for  our  American  titaniferous 
magnetites. 

REFERENCES  ON  TITANIUM 

1.  Merrill,  Non-metallic  Minerals:  109,  1904.  (General.)  2.  Merrill, 
Eng.  and  Min.  Jour.,  LXXIII :  351,  1902.  (Va.)  3.  Pratt,  U.  S. 
Geol.  Surv.,  Min.  Res.,  1903  :  309,  1904. 

TUNGSTEN 

Ores. —  The  ores  of  tungsten  are  wolframite  ([FeMn]  WO4), 
hubnerite  (MnWO4),  and  scheelite  (CaWO4).  Of  these 
wolframite  is  the  most  abundant,  and  scheelite,  the  most 
easily  reducible  ore  of  tungsten,  the  least  abundant.  Schee- 
lite is  found  in  but  few  localities  in  the  world,  and  in  the 
United  States  occurs  in  commercial  quantity  at  only  one 
locality.  Although  the  ores  of  tungsten  are  rare,  the 
quantity  available  exceeds  the  demand. 


TUNGSTEN  415 

Occurrence.  —  Most  of  the  known  American  deposits  of 
tungsten  ores  are  found  in  the  western  states,  especially 
Arizona  (1,  2,  6),  Nevada,  and  Colorado.  That  found  near 
Dragoon,  Arizona  (6),  consists  of  hiibnerite  with  subordinate 
scheelite,  and  concentrates  easily  to  a  product  yielding  WO3, 
70.22;  SiO2,  .30;  Fe,  1.90;  Mn,  19.82;  CaO,  4.87;  MgO, 
3.40.  Rich  ores  are  found  in  White  Pine  County,  Nevada, 
at  some  distance  from  the  railroad.  In  Colorado  wolframite 
and  hiibnerite  occur  in  several  counties,  and  have  been  mined 
to  some  extent.  Eastern  occurrences  are  rare,  but  scheelite 
is  found  at  Longhill,  Connecticut  (8),  where  it  occurs  along 
the  contact  of  limestone  with  diorite  and  hornblende  gneiss. 
Tungsten  is  also  found  associated  with  the  Cambrian  sili- 
ceous gold  ores  of  the  Black  Hills  region,  South  Dakota  (4), 
but  this  source  has  not  become  of  great  importance. 

Uses.  —  Tungsten  has  been  used  for  some  years  to  fix  the 
color  in  wash  goods  and  make  them  fireproof.  It  has  also 
been  employed  for  manufacturing  stained  paper.  But  the 
most  important  present  use  is  for  the  alloy  ferro-tungsten, 
or  in  the  manufacture  of  tungsten-steel.  Alloys  of  tung- 
sten, aluminum,  and  copper  are  also  made.  The  fluores- 
cent properties  of  tungstate  of  lime  make  it  useful  in  the 
Rontgen  ray  apparatus.  Tungsten  is  also  employed  for 
coloring  glass. 

Production.  —  In  1903  the  production  was  2451  short 
tons,  yielding  292  short  tons  concentrates  valued  at  143,639, 
or  $149  per  ton.  This  production  came  from  Colorado, 
Arizona,  and  Connecticut. 

In  1903  ferro-tungsten-chrome  alloys  were  imported  to 
the  value  of  118,136. 


416          ECONOMIC   GEOLOGY   OF   THE   UNITED   STATES 
REFERENCES  ON  TUNGSTEN 

1.  Blake,  Eng.  and  Min.  Jour.,  LXV :  608,  1898.  (Ariz.)  2.  Blake,  Min. 
Indus.,  VII :  720, 1899.  (Ariz.)  3.  Blake,  Amer.  Inst.  Min.  Engrs., 
Trans.,  XXVIII :  543,  1899.  4.  Irving,  Amer.  Inst.  Min.  Engrs., 
Trans.,  XXXI :  683,  1902.  (S.  Dak.)  5.  Pratt,  U.  S.  Geol.  Surv., 
Min.  Res.,  1903:  304,  1904.  (General.)  6.  Rickard,  Eng.  and 
Min.  Jour.,  LXXVIII :  263,  1904.  (Ariz.)  7.  Thomas,  Min.  and 
Met.,  XXIV  :  301.  (Ores  and  uses.)  8.  Hobbs,  U.  S.  Geol.  Surv., 
22d  Ann.  Rept.,  II :  13,  1902.  (Conn.) 


URANIUM  AND  VANADIUM 

Ores.  —  The  minerals  serving  as  the  ores  of  uranium  metals 
are  uraninite  (UO3,  UO2,  PbO,  N,  etc.),  gummite  (doubt- 
ful composition),  and  gamotite.  The  last-mentioned  also 
carries  vanadium,  as  does  also  vanadinite  [(PbCl)Pb4(VO4)3]. 
The  chief  sources  of  uraninite  are  the  mines  near  Central 
City  and  in  Montrose  County,  Colorado.  Gamotite  occurs 
in  Montrose  County,  Colorado,  and  also  in  Utah,  while 
vanadinite  has  been  found  in  some  quantity  in  the  gold 
and  silver  mining  districts  of  Arizona  and  New  Mexico. 

Uses.  —  Uranium  and  vanadium  increase  the  strength  and 
toughness  of  steel,  and  are  used  to  a  small  extent  in  the 
manufacture  of  ferro-alloys.  Uranium  oxides  are  used  for 
coloring  porcelain  and  glass,  and  vanadium  oxide  as  a 
dyeing  material.  Vanadium  compounds  are  employed  in 
making  vanadium  bronze. 

Production.  —  The  output  of  the  ores  of  these  minerals 
in  1901  came  chiefly  from  Colorado,  and  amounted  to  375 
short  tons.  In  1903,  as  a  result  of  much  prospecting  and 
developmental  work,  there  was  a  production  of  432  short 
tons  of  crude  ore.  Thirty  tons  of  concentrates  were  sold 


URANIUM   AND   VANADIUM  417 

at  a  value  of  $5625.  Most  of  the  uranium  and  vanadium 
ores  mined  in  the  United  States  are  exported,  but  a  large 
quantity  of  uranium  and  vanadium  salts  are  imported,  the 
value  of  these  in  1903  amounting  to  $13,498. 

REFERENCES  ON  URANIUM  AND  VANADIUM 

1.  Boutwell,  U.  S.  Geol.  Surv.,  Bull.  260  :  200, 1905.  (Utah.)  2.  Pratt, 
U.  S.  Geol.  Surv.,  Min.  Res.,  1901.  3.  Merrill,  Non-Metallic  Min- 
erals :  299  and  320,  1904.  (General.) 


APPENDIX   I 

STATISTICS  OF  MINERAL  PRODUCTION 

UNLESS  otherwise  stated,  the  statistics  are  in  all  cases  those  for 
1905,  the  figures  being  taken  from  the  annual  report  on  Mineral 
Resources  issued  by  the  United  States  Geological  Survey.  These 
figures,  when  first  published  by  the  Geological  Survey,  are  not 
always  to  be  regarded  as  final,  because,  when  repeated  in  the 
report  of  the  following  year,  they  are  not  infrequently  changed, 
probably  because  of  corrected  returns.  A  similar  set  of  statistics 
is  issued  annually  by  the  Engineering  and  Mining  Journal. 

COAL 


STATE 

QUANTITY 
SHORT  TONS 

VALUE 

FIELD 

SHORT  TONS 

Pennsylvania 

Anthracite  . 
Bituminous 
Illinois  .    .    . 
West  Virginia 
Ohio  .... 

77,659,850 
118,413,637 
38,434,363 
37,791,580 
25,552,950 

$141,879,000 
113,390,507 
40,577,592 
32,341,790 
26,486,740 

Anthracite  (Pa.,  Colo., 
N.  Mex.) 
Triassic 
Appalachian 
Northern 
Eastern  Interior 

77,734,673 
1,557 
212,830,030 
1,473,211 
65,255,541 

Indiana  .    . 
Alabama 
Colorado     . 
Kentucky   . 
Iowa  .    . 
Kansas  .    . 
Tennessee  . 
Wyoming   . 

11,895,252 
11,866,099 
8,826,429 
8,432,523 
6,798,609 
6,423,979 
5,963,396 
5,602,021 

12,492,255 
14,387,721 
10,810,978 
8,385,232 
10,586,381 
9,350,542 
6,797,550 
7,336,951 

Western 
Rocky  Mountain,  etc. 
Pacific  coast 
Alaska 

23,265,750 
19,303,188 
3,051,617 
3,774 

Total  United  States  production  in  1905,  392,919,341  short  tons;  value, 
$476,756,963.  Exports  in  1905 :  2,229,983  long  tons  anthracite ;  value,  $11,104,654 ; 
6,959,265  long  tons  bituminous;  value,  $17,867,964. 

PRODUCTION  OF  LEADING  COAL-PRODUCING  COUNTRIES 


COUNTRY 

United  States  (1905)      . 
Great  Britain  (1905)      . 
Germany  (1905) 

• 

SHORT  TONS 
392,919,341 
264,464,408 
191  576  074 

Austria-Hungary  (1904) 
France  (1904) 
Belgium  (1905)       . 
Russia  and  Finland  (1904)    . 
Japan  (1903)  .... 

45,209,933 
37,663,349 
24,078,862 
21,294,639 
11,120,934 

419 


420 


APPENDIX   I 


PETROLEUM  SERIES 


PETROLEUM 

NATURAL  GAS 

STATE 

BARRELS 

VALUE 

STATE 

VALUE 

33,427,473 
28,136,189 
16,346,660 

12,013,495 
11,578,110 
10,9H4,247 
10,437,195 
8,910,416 
1,217,337 
134,717,580 

$8,201,846 
7,552,262 
17,054,877 

6,546,398 
16,132,631 
9,404,909 
14,653,278 
1,601,325 
943,211 
884,157,399 

Pennsylvania 
West  Virginia 
Ohio     .    .    . 
Indiana     .     . 
Kansas      .     . 
New  York     . 
Kentucky  and 
Tennessee  .     .     . 
Indian  Territory 
and  Oklahoma    . 
Total,  United  States 

$19,197,336 
10,075,804 
5,721,462 
3,094,134 
2,2(51,836 
623,251 

237,590 

130,137 

$41,562,855 

Texas     
Ohio 

Kansas,  Oklahoma, 
Indian  Territory  .     . 
West  Virginia    .    .    . 
Indiana      
Pennsylvania     .    .    . 

Kentucky  
Total,  United  States 

PRODUCTION  OF  ASPHALTUM  AND  BITU- 
MINOUS ROCK  IN  THE  UNITED  STATES 

PRODUCTION  OF  ASPHALTUM 
BY  STATES 

VARIETY 

SHORT 
TONS 

VALUE 

STATE 

SHORT 
TONS 

VALUE 

Bituminous  sandstone    . 
Bituminous  limestone     . 
Mastic  
Hard  and  refined  gum    . 
Liquid  or  maltha   .     .     . 
Wurtzilite     

39,273 
6,029 
2,200 
3,036 
3,139 
500 
10,916 
5 
50,169 

$94,972 
42,000 
22,000 
41,438 
34,292 
44,000 
47,040 
1,500 
430,911 

California  .     .     . 
Kentucky    .     .     . 
Indian  Territory 
Arkansas    .     .     . 
Utah  

91,076 
8,834 
2,936 
1,000 
11,421 

$568,403 
66,420 
27,790 
3,000 
92,540 

Gilsonite  

Oil  asphaltum  .... 
Total    

115,267 

$758,153 

WORLD'S  PRODUCTION  OF 
PETROLEUM 

WORLD'S  PRODUCTION  OF  ASPHAL- 
TUM IN  1904 

COUNTRY 

BARRELS  (42  gal.) 

COUNTRY 

SHORT 
TONS 

VALUE 

United  States  .... 
Russia      
Sumatra,  Java,  Borneo 
Galicia 

134,717,580 
54,960,270 
7,768,0001 
5,765,317 
4,420,987 
4,137,098 
1,341,157 
634.095 
560,<)63 
37,720 
25,0001 
30,0001 

United  States  2     .    . 
Trinidad  

64,167 
152,392 
101,121 
250,222 
123,347 
4,146 
4,029 
14,910 

$420,701 
727,552 
212,058 
289,415 
307,985 
7,259 
59,386 
262,809 

Roumania    
India   

Italy 

Spam  
Austria-Hungary  .    . 
Venezuela    .... 

Canada    

Germany      
Peru    

Italy 

All  others     
Total  

214,398,187 

Exports  in  1905,  1,220,513,587  gal 
Ions;  value,  $79,640,929. 

Refined  oil  imports,  13,725,720  gal 
Ions;  value,  $672,127. 

1  Estimated. 


Imports  of  crude  asphaltum,  100,596 
shert  tons,  valued  at  $479,296. 


2  Exclusive  of  oil  asphaltum. 


APPENDIX  I 


421 


BUILDING  STONES 

CLAY   PRODUCTS 

PRODUCTION  OF  BUILDING  STONES  IN 
THE  UNITED  STATES 

PRODUCTION  OF  CLAY  PRODUCTS  IN 
THE  UNITED  STATES 

KIND 

VALUE 

STATE 

VALUE 

Granite 

$17,563,139 
3,074,554 
7,129,071 
5,496,207 
10,006,774 
26,025,210 

Ohio 

$28,303,039 
19,124,553 
16,699,525 
14,486,347 
12,361,786 
6,499,573 
$149,697,188 

Trap     

Pennsylvania      .... 
New  Jersey    

Marble      

Slate    

New  York 

Sandstone     

Illinois  

Limestone     

Indiana  

Total    

869,294,955 

Total,  United  States     .    . 

CEMENTS 


PRODUCTION  OF  PORTLAND  CEMENT 
IN  THE  UNITED  STATES 

PRODUCTION  OF  NATURAL  CEMENT 
IN  THE  UNITED  STATES 

STATE 

QUANTITY 
BARRELS 

VALUE 

STATE 

QUANTITY 

BARRELS 

VALUE 

Pennsylvania     . 
Missouri    .     .     . 
New  Jersey    .     . 
Indiana      .     .     . 
Michigan  .     .     . 
New  York.     .     . 
Illinois  .... 
Ohio       .... 

13,813,487 
3,879,542 
3,654,777 
3,127,042 
2,773,283 
2,111,411 
1,545,500 
1,312,977 
1,225,429 
35,246,812 

$11,195,940 
4,164,974 
2,775,678 
3,134,219 
2,921,507 
2,044,253 
1,741,150 
1,390,481 
1,671,816 
$33,245,867 

New  York    .    . 
Pennsylvania 
Indiana    . 
Illinois     . 
Kansas     . 
Kentucky 
Wisconsin 
Minnesota 
Georgia    . 
Total,  U.S.    .    . 

1,926,837 
748,057 
527,600 
368,645 
230,686 
207,500 
139,128 
115,314 
89,167 
4,473,049 

$1,332,809 
306,552 
211,040 
116,549 
110,750 
83,000 
63,737 
57,643 
51,040 
$2,413,052 

California  .     .     . 
Total,  U.S.    .     . 

Imports  of  hydraulic  cement  in  1905,  846,577  barrels.  Exports  of  hydraulic 
cement  in  1905,  897,686  barrels;  value,  $1,387,906.  Production  of  slag  cement  in 
United  States,  382,447  barrels ;  value,  $272,614. 

SALT 


PRODUCTION  OF  SALT  IN  THE  UNITED 
STATES 


WORLD'S  PRODUCTION  OF  SALT  IN 
1904 


STATE 

BARRELS 

VALUE 

COUNTBY 

SHORT 
TONS 

VALUE 

Michigan     . 
New  York  .    .     . 
Ohio   

9,492,173 
8,359,121 
2,526,558 

$1,851,332 
2,167,931 
565,946 

United  States     . 
United  Kingdom 
France   ana   Al- 

3,084,200 
2,118,629 

$6,021,222 
2,900,375 

Kansas   .... 

2,098,585 

576,139 

geria  .... 

1,292,557 

3,660,052 

Louisiana    .     .     . 

1,055,186 

303,507 

German  Empire 

1,875,733 

4,693,122 

California   .     .     . 

664,099 

188,330 

Japan  (1903)  .     . 

724,750 

4,692,539 

Texas      .... 

444,832 

142,993 

Italy  

511,827 

713,595 

West  Virginia     . 
Utah  .... 

202,151 
177,342 

74,063 
135,465 

Austro-Hungary 
Russia  .... 

595,335 
not  avail 

16,024,783 
able 

Total,  U.S.      .    . 

25,966,122 

$6,095,922 

Spain     .... 
India     .... 

599,292 
1,236,702 

738,348 

Canada  .... 

68,777 

318,628 

Exports  in  1905,  50,886,454  pounds ;  value,  $190,376. 
Imports  in  1905,  308,572,025  pounds;  value,  $496,734. 


422 


APPENDIX  I 


BORAX 

Production  in  California,  46,334  short  tons  crude  borax,  valued 
at  $1,019,154. 

Imports  of   borax,  borates,  and  boric  acid,    863,460  pounds, 
valued  at  $32,800. 

WORLD'S  PRODUCTION  OF  BORAX  IN  1904 


COUNTRY 

METKIO  TONS 

Coi'XTKY 

MKTRIC  TONS 

United  States     .    .    . 
Bolivia 

42,034 
1  1% 

Germany  
Italy     .' 

135 
2624 

Chile  (1903)     .... 

16879 

Peru     

2,675 

India      

'212 

GYPSUM 


PRODUCTION  OF  GYPSUM  IN  THE 
UNITED  STATES 

WORLD'S  PRODUCTION  OF  GYPSUM 
IN  1904 

STATES 

SHORT 
TONS 

VALUE 

COUNTRY 

SHOBT 
TONS 

VALUE 

Michigan  ... 
Iowa     
New  York     .    . 
Oklahoma,  Texas 
Ohio,  Virginia  . 
Kansas     ... 
California,     Nevada, 

299,585 
179,016 
153,367 
148,947 
134,276 
47,276 

29,155 
26,880 

24,700 

$143,597 
114,354 
151,272 
148,947 
134,474 
32,940 

39,947 
26,930 

29,500 

France   .    .    . 
United  States 
Canada  .    .    . 
Great  Britain 
German  Empire 
Algeria  .     .     . 
Cyprus  .    .    . 

1,749,875 
940,917 
298,211 
262,086 
25,095 
386 
12,449 

$2,916,483 
2,784,325 
316,436 
354,138 
17,307 
169 
31,721 

Wyoming      .... 
Utah,  Montana,  South 
Dakota,  New  Mex- 
ico      

Total    

1,043,202 

$821,967 

Imports  of  ground  and  unground  gyps 
FERTILIZERS 

am,  and  plaster  of  Paris,  $446,152. 
ABRASIVES 

PRODUCTION  OF  PHOSPHATE  IN  THE 
UNITED  STATES 

PRODUCTION  OF  ABRASIVES  IN  THE 
UNITED  STATES 

STATE 

LONG 
TONS 

VALUE 

KINDS 

VALUE 

Florida 

1,194,106 
270,225 
482,859 

$4,251,845 
878,169 
1,633,389 

Oilstones  and  scythestones 
Grindstones  and  pulpstones 
Buhrstones  and  millstones 

$244,346 
777,606 
37,974 
5,540 
64,637 
88,118 
148,095 
61,464 
$1,427,780 
701,400 
654,821 
$2,784,001 

South  Carolina   .    . 
Tennessee  .... 

Total      

1,947,190 

$6,763,403 

Infusorial  earth  and  tripoli 
Crystalline  quartz      .     .    . 
Garnet 

Imports  of  phosphates  and  other  fertili- 
zers in  1905,  $832,216. 

Corundum  and  emery     .    . 
Total                   

Artificial  abrasives     .    .    . 

Grand  total 

APPENDIX   I  423 

PRODUCTION  OF  MINOR  NON-METALLIC  MINERALS  IN  UNITED  STATES 


KIND 

QUANTITY 

VALUE 

IMPORTS  VALUE 

3  109  sh  t 

$42  975 

$846479 

Barite         .... 

102,262 

Missouri.    .    .         .             .    . 

26  761  sh  t 

84095 

North  Carolina    
Tennessee  and  Kentucky  .    .    . 
Virginia      

5,519  sh.  t. 
9,487  sh.  t. 
6,468  sh.  t. 

21,545 
15,325 
27,838 

Feldspar    ....         .... 

48,235 
35  419  sh  t 

148,803 
226  157 

1  156  sh  t 

8  200 

Illinois    

33  275  sh  t 

220  206 

Kentucky    

22  694  sh   t 

132  362 

Tennessee    

260  sh.  t. 

1,720 

Fuller's  earth     
Glass  sand      
Graphite             .    .    . 

57,385 
25,178  sh.  t. 
1,030,334  sh.  t. 

362,488 
214,497 
1,083,730 

74,006  (1904) 

Crystalline  

6,036,567  Ib. 
21  953  sh  t 

[       318,211 

Artificial     
World's  production  (1904)     .     . 
Magnesite  

4,591,550  Ib. 
105,923  sh.  t. 
3,933  sh.  t. 

313,980 
3,042,199 
15,221 

63,264 

Ocher      

13,402  sh.  t. 
689  sh  t 

126,351 
17  004 

92,553 
21  451 

Metallic  paint          .    . 

16  489  sh  t 

176  722 

10  494  sh  t 

120  430 

Slate       .    .    .    .    . 

5  181  sh  t 

44  108 

47  590  081  eal 

6  811  611 

926  357  1 

Monazite    . 

1  352  418  2  Ibs 

163  908 

326  350 

34  998  513 

Sulphur      
Pyrite    
Quartz  
Talc  and  soapstone     .... 
New  Jersey  and  Pennsylvania 
North  Carolina  and  Virginia 
Massachusetts  and  Vermont 
California,  Georgia,  Maryland 
and  Washington  .... 
New  York  

181,677  L  t. 
253,000  1.  t. 
51,145  sh.  t. 

5,796  sh.  t. 
21,700  sh.  t. 
10,188  sh.  t. 

2,450  sh.  t. 
56,500  sh.  t. 

3,706,560 
938,492 
104,109 

38,241 
499,780 
75,405 

23,636 
445,000 

1,567,485 
1,774,379 

48,225  (talc) 

96,634 

1,082,062 

1  Includes  artificial.      2  Includes  a  small  quantity  of  zircon  and  coluinbite. 


424 


APPENDIX  I 


METALLIC  MINERALS 
IRON  ORES 


PRODUCTION  OF  IRON  ORES  IN 
THE  UNITED  STATES 

PRODUCTION  OF  MOST  IMPORTANT  IRON 
ORE  PRODUCING  COUNTRIES 

STATE 

LONG  TONS 

COUNTRY 

QUANTITY 

LONG  TONS 

PER  CENT 
WORLD'S 
PRODUCTION 

Minnesota      .... 
Michigan  

21,735,182 
10,885,902 
3,782,831 
1.139,937 
859,283 
808,717 

752,045 
734,770 
526,271 
133,471 
1  167  724 

United  States    .    . 
Germany  and 
Luxemburg    .     . 
Great  Britain     .     . 
Spain    

35,019,308 

21,230,650 
13,715,645 
8,304,153 
6,219,541 

5,648,227 
3,677,841 

3,269,175 

34.41 

20.86 
13.48 
8.16 
6.11 

5.55 
3.61 

3.21 

New  York     .     .     . 
Wisconsin      .    .    . 
Pennsylvania     .     . 
Virginia  and 
West  Virginia    . 
Tennessee      .     .    . 
New  Jersey  .    .    . 
Colorado  

France 

Russia  and 
Finland  i    .    .     . 
Sweden      .... 
Austria  and 
Hungary2  .    .    . 

Total    .    .    . 

42,526,133 
$75,165,604 

Total8  

101,185,000 

100.00 

Value  of  the  above     . 

Imports  in  1905,  845,651  long  tons;  value,  $2,062,161. 
Exports  in  1905,  208,017  long  tons ;  value,  $530,457. 


COPPER  ORES 


PRODUCTION  OF  COFFER  IN  UNITED 

STATES 

WORLD'S  COFFER  PRODUCTION  IN 
1905 

STATE  OR  TERRITORY 

POUNDS 

COUNTRY 

LONG 
TONS 

Montana  

314,750,582 
235,908,150 
230,287,992 
58,153,393 
16,697,489 
15,134,960 
9,404,830* 
5,334,192 
16,2:36,255 

United  States  

402,637 
70,185 
44,810 
35,910 
29,165 
22,160 
96,385 
701  ,252 

Arizona    
Michigan  . 

Mexico                           .    .    . 

Spain  and  Portugal  .... 
Japan  
Chile    
Germany      
All  others    
Total  

Utah        . 

California     
Tenn.  and  Southern  States 
Colorado  
New  Mexico      

All  others     

Total    .    .    . 

901,907,843 

Imports  of  copper  ore  and  matte,  $5,765,238. 
Exports  of  copper  ore  and  metal,  $86,408,731. 


1  1902.  2  Includes  Bosnia-Herzegovina. 

4  Including  copper  smelters. 


8  Approximate. 


APPENDIX   I 


425 


LEAD  AND  ZINC 
PRODUCTION  or  LEAD  AND  SPELTEB  IN  THE  UNITED  STATES 

SHORT  TONS 

Lead 307,000 

Spelter 


LEAD  CONTENT  OF  AMERICAN 
ORES  SMELTED  IN  1905 

PRODUCTION  OF  SPELTER  BY 
STATES 

STATE  OK  TERRITORY 

SllORT 

TONS 

STATES 

SHORT 
TONS 

Colorado  
Idaho  

56,638 
99,027 
44,99(5 
2,207 
1,232 
2,206 
2,091 
116 
66 

101 
104,058 

Eastern  and  Southern    .    .    . 
Illinois  
Kansas  

24,513 
46,606 
114,287 
11,844 
6,599 

Utah    

Missouri    
Colorado    
Total     

New  Mexico     
Nevada    
Arizona   

203,849 

California    

WORLD'S  PRODUCTION  OF 
SPELTER 

Oregon,  Alaska,  South 
Dakota,  and  Texas     .     . 
Missouri,  Kansas,  Wisconsin, 
Illinois,    Iowa,  Virginia, 
and  Kentucky    .... 
Total 

COUNTRY 

SHOUT 
TONS 

312,728 

18,709. 
,611. 
in    1905, 

Belgium     

160,345 
74,127 
15,176 
56,140 
55,524 
143,243 
10,315 
8,422 
203,849 
727,141 

Imports  of  lead  in  1905,  $1,1 
Imports  of  zinc  in  1905,  $61 
Exports  of   domestic  zinc 
$1,690,700. 

Rhine  district 

Holland         

Great  Britain 

France  and  Spain  

Silesia 

Austria  and  Italy  
Poland  
United  States                      • 

Total     

ALUMINUM 

United  States  production  in  1905,  11,347,000  pounds.1 
Imports    in    1903    of    crude    and    manufactured    aluminum, 
$143,471. 

WORLD'S  PRODUCTION  OF  ALUMINUM  IN  1904 


COUNTRY 

QUANTITY 
METRIC  TONS 

VALUB 

United  States   

3,402 

$2,325,000 

Switzerland                                       .     .     . 

2500 

1  413  125 

France      
United  Kingdom  

1,700 
650 

849,025 
328,250 

8,252 

$4,915,400 

Consumption. 


426 


APPENDIX   I 
GOLD  AND  SILVER 


PRODUCTION  OF  GOLD  AND  SILVER  IN  1904,  BY  STATES  AND 
TERRITORIES 


STATE  AND  TEBBITOBY 

GOLD 

SILVER 

QUANTITY 
FINE  Oz. 

VALUE 

QUANTITY 
FINE  oz. 

COMMERCIAL 
VALUE 

1,417 
443,177 
168,274 
901,484 
1,183,518 
4,668 
82,739 
116 

206,419 
244,823 
18,476 
5,994 
68,321 
5,892 
356,264 
208 
9 
202,675 
184 
15,214 
837 

$29,300 
9,160,458 
3,478,532 
18,633,676 
24,463,322 
96,900 
1,710,365 
2,400 

4,267,062 
5,060,494 
381,930 
123,900 
1.412,186 
121,800 
7,363,977 
4,300 
186 
4,189,292 
3,800 
314,463 
17,305 

200 
193,695 
2,314,940 
1,480,589 
13,947,635 
1,500 
7,666,382 

122,807 
12,817,285 
4,268,123 
214,553 
14,800 
132,077 
500 
161,611 
59,200 
385,576 
12,049,446 
6,700 
157,598 
4,647 

$116 
110,405 
1,325,303 
843,936 
7,985,028 
870 
4,389,004 

70,000 
7,334,146 
2,432,830 
124,103 
8,584 
75,284 
290 
92,522 
34,336 
213,935 
6,898,308 
3,886 
89,831 
2,661 

Alaska  

Arizona     
California      

Colorado 

Georgia     .         ... 

Idaho    

Michigan             ...         .     . 

Montana    

Nevada      

North  Carolina  

South  Carolina  

South  Dakota    
Tennessee  

Texas    
Utah     

Virginia    

Washington  .             ... 

Wyoming  

Total     ...         ... 

3,910,729 

$80,835,648 

55,999,864 

BAUXITE 


PRODUCTION  OF  BAUXITE  IN 
UNITED  STATES 


WORLD'S  PRODUCTION  OF  BAUXITE 
IN  1904 


STATE 

LONG  TONS 

COUNTRY 

LONG  TONS 

VALUE 

Georgia     ) 

15,173 

United  States  .    . 

47,661 

$235,704 

Alabama  j 
Arkansas     

32,956 

France    .... 
United  Kingdom  . 

74,449 
8,700 

8,340 

Total 

48  129 

Total 

130810 

375,273 

Value  oi  above     .... 

$240,292 

Imports  of  bauxite,  11,726  long  tons ;  value,  $46,517. 
Exports  of  bauxite,  none  since  1901. 


APPENDIX   I 


427 


MANGANESE 


PRODUCTION  OF  MANGANESE  IN 
THE  UNITED  STATES 

PRODUCTION  OF  MANGANESE  ORES  BY 
KINDS  IN  THE  UNITED  STATES 

STATE 

QUANTITY 
LONG 
TONS 

VALUE 

KIND 

LONG 
TONS 

VALUE 

Virginia     .     .     . 
Georgia     .     .     . 
Tennessee  .     .     . 
California  .     .     . 
Total     .    .  '  ,    . 

3,947 
150 
20 
1 

$35,209 
900 
100 
5 

Manganese  ores    .    .    . 
Manganiferous  iron  ores 
Manganiferous  silver 

4,118 
709,256 

81,738 
90,289 

.136,214 
1,554,9(59 

270,299 
20.289 

4,118 

$36,214 

Manganiferous  zinc 

Total 

945,401 

$1,951,771 

Imports  of  manganese  ores  in  1905,  257,033  long  tons ;  valued  at  $1,952,407. 


MERCURY 
PRODUCTION  OF  MERCURY  IN  THE  UNITED  STATES 


STATE 

QUANTITY 
FLASKS,  76J  LB. 

VALUE 

California  ... 

24635 

$886081 

Texas 

4  723 

173362 

43 

1  677 

Utah  

1,050 

42,000 

Total      

30451 

$1  103  120 

Imports  of  mercury  in  1905,  2690  Ib. ;  value,  $1710.     Exports  of  mercury  in 
1905, 13,534  flasks ;  value,  $489,756. 


WORLD'S  PRODUCTION  OP  MERCURY  IN  1904 


COUNTEY 

QUANTITY 
METBIO  TONS 

VALUE 

United  States      •    » 

1  188 

$1  503  795 

Austria  ....                  . 

536 

602  236 

Italy  .... 

355 

396  335 

Russia    .    .    . 

393 

441  597 

Spain     

1,020 

1,146,132 

Total      

3  492 

$4  090  097 

428  APPENDIX   I 

PRODUCTION  OF  MINOR  METALS  IN  THE  UNITED  STATES 


KIND 

QUANTITY 

VALUE 

IMPORTS 
VALUE 

3,240  sh.  t. 
1,507,386  Ib. 
2,288  Ib. 
25  Ib. 

90  sh.  t. 

318  oz. 
Practically 
803 
4 

$705,787 
35,210 
4,187 
375 

19,410 

5,320 
none 
268,676 
375 

$53,0261 
256,5402 
318,007 

2,173,263 
26,316,023 

Arsenic  (white)     

Molybdenum    ] 
Nickel 

Titanium          |    

Cobalt              J 

Tin                

1  Crude  antimony  and  ore. 


2  Arsenic  and  compounds. 


APPENDIX  II 

THIS  contains  a  list  of  the  more  important  papers  which  have 
been  issued  since  the  appearance  of  the  first  edition.  Except  in 
the  case  of  a  few  important  mineral  products,  such  as  Coal  and 
Gold,  the  references  under  each  kind  of  material  are  arranged 
alphabetically  by  authors. 

COAL 

GENERAL.  Reports  on  Fuel-testing  Operations  at  St.  Louis ;  U.  S.  Geol. 
Surv.,  Prof.  Paper  48,  and  Bulls.  261  and  290.  Campbell,  Amer.  Inst. 
Min.  Engrs.,  Bimonthly  Bull.,  March,  1906.  (Classification.)  Campbell, 
Econ.  Geol.,  I,  No.  1,  1905.  (Origin.)  Smith,  Econ.  Geol.,  June, 
1906.  (Criticism  of  Campbell's  theory.)  Ford,  Nat.  Ass'n.  Coll.  Mgrs., 
June  30,  1906.  (Origin.)  Parr,  Jour.  Amer.  Chem.  Soc.,  Oct.,  1906. 
(Classification.) 

AREAL.  Alaska:  Collier,  U.  S.  Geol.  Surv.,  Bull.  278.  (Cape  Lisburne.) 
Martin,  Ibid.,  Bull.  284.  (Bering  Kiver.)  Stone,  Ibid.,  Bull.  277. 
(Kachernak  Bay.) —California :  Arnold,  U.  S.  Geol.  Surv.,  Bull.  285. 
(Mount  Diablo  Range. )  — Colorado  :  Schrader,  U.  S.  Geol.  Surv.,  Bull. 
285.  (Durango-Gallup  field.)  Fenneman  and  Gale,  U.  S.  Geol.  Surv., 
Bull.  285.  (Yampa  field.)— Illinois  :  Parr,  Illinois  Geol.  Surv.,  Bull 
3,  1900.  — Kentucky  :  Ashley  and  Glenn,  U.  S.  Geol.  Surv.,  Prof.  Paper 
49.  (Cumberland  Gap  field.)  Crandall,  Ky.  Geol.  Surv.,  Bull.  4,  1905. 
(Big  Sandy  Valley. )  —  Montana  :  Rowe,  Univ.  of  Mont.,  Bull.  4.  —  New 
Mexico  :  Schrader,  U.  S.  Geol.  Surv.,  Bull.  285.  (Durango-Gallup  field.) 
Lee,  U.  S.  Geol.  Surv.,  Bull.  285.  (Engle  field.)— North  Dakota: 
Wilder,  Econ.  Geol.,  July-Aug.,  1906.  (Lignites. )—  Pennsylvania  : 
Ashley,  U.S.  Geol.  Surv.,  Bull.  285.  (Clearfield  field.)  — Utah:  Taff, 
Ibid.  (Weber  River  field.)  Taff,  Ibid.  (Book  Cliffs  field.)  Richard- 
son, Ibid.  (Sanpete  Co.) — Virginia:  Randolph,  Cassier's  Mag., 
Feb.,  1905.  (Anthracite.) —  Wyoming  :  Trumbull,  Bull.  7,  Wyo.  Sch. 
of  M. 

PEAT 

Hindshaw,  U.  S.  Geol.  Surv.,  Min.  Res.,  1904.     (General  U.  S.)     McCourt 
and  Parmelee,  N.  J.  Geol.  Surv.,   1905:  223.      (N.  J.  and  general.) 
Wilder  and  Savage,  la.  Geol.  Surv.,  1905.     (Iowa.) 
429 


430  APPENDIX  II 


PETROLEUM 

Arnold,  U.  S.  Geol.  Surv.,  Bull.  285.  (California.)  Ashburner,  Amer.  Inst. 
Min.  Engrs.,  XVI:  906.  (New  York.)  Bishop,  N.  Y.  State  Museum, 
22d  Ann.  Kept.  N.  Y.  State  Geologist :  r.  63.  (New  York.)  Blatchley, 
111.  Geol.  Surv.,  Bull.  2.  (S.  E.  Illinois.)  Clapp,  U.  S.  Geol.  Surv., 
Bull.  285.  (Greene  Co.,  Pa.)  Coste,  Amer.  Inst.  Min.  Engrs.,  XXXV : 
288.  (Volcanic  origin.)  Fenneman,  U.  S.  Geol.  Surv.,  Bull.  282. 
(Texas-Louisiana  field.)  Gould,  Eng.  and  Min.  Jour.,  Aug.  11,  1906. 
(Kansas-Oklahoma.)  Kichardson,  Jour.  Frank.  Inst.,  July,  1906. 
(North  America.)  Veatch,  U.  S.  Geol.  Surv.,  Bull.  285.  (Uinta  Co., 
Wyo.) 

NATURAL  GAS 

Adams,  Haworth,  Crane,  U.  S.  Geol.  Surv.,  Bull.  238.  (Kansas.)  Newland, 
N.  Y.  State  Mus.,  Bull.  93  :  943.  (New  York.) 

ASPHALT 

Taff  and  Smith,  U.  S.  Geol.  Surv.,  Bull.  285.  (Utah  ozokerite.)  Eldridge, 
Econ.  Geol.,  1 :  437.  (Asphalt  vein  formation.) 

BUILDING  STONES 

Dale,  U.  S.  Geol.  Surv.,  Bull.  285.  (Maine  slate.)  Dale  and  others,  U.  S. 
Geol.  Surv.,  Bull.  275.  (United  States  slate.)  McCourt,  N.  Y.  State 
Mus.,  Bull.  100.  (Fire  tests,  N.  Y.  stones.)  Watson,  Laney,  and  Merrill, 
N.  Ca.  Geol.  Surv.,  Bull.  2.  (North  Carolina  general.) 

CLAYS 

Kies,  Clays,  their  Occurrence,  Properties,  and  Uses,  New  York,  1906. 
(Wiley  and  Sons.)  Ashley,  U.  S.  Geol.  Surv.,  Bull.  285.  (Clearfield 
Co.,  Pa.)  Crider,  Ibid.  (W.  Kentucky.)  Fuller,  Ibid.  (Cape  Cod.) 
Phalen,  Ibid.  (N.  W.  Kentucky.)  Siebenthal,  Ibid.  (Bentonite  in 
Wyo.)  Grimsley  and  Grout,  W.  Va.  Geol.  Surv.,  III.  (West  Virginia.) 
Logan  and  Hand,  Bull.  Miss.  Agric.  and  Mech.  Coll.,  II,  No.  3.  (Mis- 
sissippi.) Ries,  Amer.  Inst.  Min.  Engrs.,  Bimonthly  Bull.,  Sept., 
1906.  (Texas.)  Ries,  Va.  Geol.  Surv.,  Bull.  II.  (Virginia.) 

LIME  AND  CALCAREOUS   CEMENTS 

Eckel,  Cements,  Limes,  and  Plasters,  New  York,  1906.  (Wiley  and  Sons.) 
Meade,  Portland  Cement,  Easton,  1906.  (Chemical  Publishing  Co.) 
Bastin,  U.  S.  Geol.  Surv.,  Bull.  285.  (Knox  Co.,  Me.)  Bain  and  Eckel, 
la.  Geol.  Surv.,  XV :  33.  (Iowa.)  Eckel,  U.  S.  Geol.  Surv.,  Bull.  285. 
(Tenn.-Va.  district.)  Grimsley,  W.  Va.  Geol.  Surv.,  III.  (West  Vir- 
ginia.) Kummel,  N.  J.  Geol.  Surv.,  1905:  173.  (Sussex  and  Warren 
counties  limestones.)  Landes,  U.  S.  Geol.  Surv.,  Bull.  285.  (Washing- 
ton.) Orton  and  Peppel,  Ohio  Geol.  Surv.,  4th  ser.,  Bull.  4.  (Ohio.) 


APPENDIX  II  431 


SALT 

Bownocker,  Ohio  Geol.  Surv.,  4th  ser.,  Bull.  8.  (Ohio.)  Lane,  Jour.  Geol., 
XIV:  221.  (Chemical  evolution  of  ocean.) 

GYPSUM 

Siebenthal,  U.  S.  Geol.  Surv.,  Bull.  285.  (Laramie  dist.,  Wyo.,  and  Un- 
compahgre  region,  Colo.) 

FERTILIZERS 

Jumeau,  Annales  de  Chimie,  June  15,  1906.  (United  States.)  Prather, 
Jour.  Geol.,  Sept. -Oct.,  1905.  (N.  J.  glauconite.) 

ABRASIVES 

For  general  on  diatomaceous  earth  see :  Bull.  Imp.  Inst.,  Ill,  No.  1 :  88  and 
Can.  Geol.  Surv.,  Ann.  Kept.,  XV,  Pt.  S.  Magnus,  N.  Y.  State  Mus., 
57th  Kept.,  I  :  158.  (New  York.)  Newland,  Eng.  and  Min.  Jour., 
Jan.  6,  1906.  (New  York  garnet.)  Pratt,  N.  Ca.  Geol.  Surv.,  I. 
(Corundum,  North  Carolina.)  Pratt,  U.  S.  Geol.  Surv.,  Bull.  269. 
(Corundum,  United  States.)  Desau,  Min.  World,  Dec.  31,  1904. 
(Borts  and  carbons.) 

MINOR  MINERALS 

ASBESTOS  :  Cirkel,  Can.  Dept.  Int.,  Mines  Branch,  1905.  (Occurrence  and 
uses.)  Pratt,  Min.  World,  July  8,  1905.  (Arizona.)  —  BAKITE  :  Dick- 
son,  Sch.  of  M.  Quart.,  XXIII :  366.  (Conc'n  in  limestone.)  Lakes, 
Min.  Rep.,  Aug.  16, 1906.  (Idaho.)  —FELDSPAR:  Hopkins,  Min.  Indus., 
VII:  262.  (General.)  Also  A.  A.  A.  S.,  XL VII :  293.  (S.  E.  Penn- 
sylvania.) Kies,  U.  S.  Geol.  Surv.,  Min.  Res.,  1901  :  937.  (General.)  — 
FLUORSPAR :  Fohs,  Eng.  and  Min.  Jour.,  Jan.  6, 1906.  (U.  S.  industry.) 
—  GLASS  SAND:  Burchard,  U.  S.  Geol.  Surv.,  Bull.  285.  (General  and 
Missouri.)  Stose,  ibid.  (E.  West  Virginia.)—  GRAPHITE  :  Newland, 
Eng.  and  Min.  Jour.,  Jan.  13,  1906.  (New  York.)  —  MAGNESITE  :  Hess. 
U.  S.  Geol.  Surv.,  Bull.  285.  (Calif ornia.)  —  MICA  :  Cirkel,  Can.  Dept. 
Int.,  Mines  Branch,  1905.  (Occurrence,  etc.)  Colles,  Mica,  and 
the  Mica  Industry.  New  York,  1906.  (General.)  —MOLDING  SAND: 
Field,  Iron  Tr.  Rev.,  Mar.  15,  1906.  Kummel  and  Hamilton,  N.  J. 
Geol.  Surv.,  1904:  187.  (New  Jersey.)  Palmer,  Amer.  Mach.,  Oct.  5, 
1905.  (Core  sands.)  Ries,  Foundry,  July,  1906.  (Laboratory  exami- 
nation methods.)  Visonneau,  Bull,  de  la  Soc.  d'Enc.  pour  1'Ind.  Nat., 
Rev.  de  Met.,  July  1,  1906.  (General.)  —PRECIOUS  STONES  :  Crookes, 
Min.  Jour.,  Sept.  9,  16,  23,  and  30,  1905.  (Diamonds.)  Kunz,  Calif. 
St.  Min.  Bur.,  Bull.  37.  (Calif.)  See  also  same  author  in  U.  S.  Geol. 
Surv.,  Min.  Res.,  1904  and  1905.  —SULPHUR  AND  PYRITE  :  Nason,  Eng. 


432  APPENDIX  II 

and  Min.  Jour.,  July  28,  1906.  (Origin  Appalachian  pyrites.)  Thomas, 
Min.  World,  Aug.  25,  1906.  (Texas  sulphur. )  — TALC  :  Peck,  N.  J. 
Geol.  Surv.,  1904:  163.  (N.  J.-Pa.)  —  WATBE  :  Gautier,  Econ.  Geol., 
July- Aug.,  1906.  (Genesis  of  thermal  waters.)  Numerous  water- 
supply  bulletins  issued  by  U.  S.  Geol.  Surv.  —  SOILS  :  Hilgard,  Soils, 
New  York,  1906.  (Macmillan  Co.)  Merrill,  Rocks,  Eock-weathering, 
and  Soils,  New  York,  1906.  (Macmillan  Co.) 

ORE  DEPOSITS 

Bain,  Econ.  Geol.,  I.  No.  4.  (Classification.)  Beck,  Trans.  Geol.  Soc.  S. 
Afr.,  VIII :  147.  (Ore  veins  and  pegmatites.)  Demaret,  Annal.  des  M. 
de  Belg.,  XI:  542.  (Genesis.)  Kemp,  Econ.  Geol.,  I,  No.  3.  (Forma- 
tion of  ore  deposits.)  Kemp,  Min.  and  Sci.  Pr.,  March  31,  1906. 
(Garnet  zones.)  Kemp,  Econ.  Geol.,  I,  No.  1.  (Sec'y  enrichment  cop- 
per ores.)  Lane,  Jour.  Can.  Mg.  Inst.,  IX.  (Magmatic  segregation.) 
Lindgren,  Econ.  Geol.,  Oct.  to  Nov.,  1905.  (Ore  deposition  and  deep 
mining.)  Miller,  Elements  of  Mining  Geology  and  Metallurgy,  Denver, 
1906.  Parks,  Inst.  Mg.  and  Met.,  Apr.  13,  1905.  (Border  segregation.) 
Park,  A  Text-book  of  Mining  Geology,  Philadelphia,  1906.  Read, 
Amer.  Inst.  Min.  Engrs.,  Bimonthly  Bull.,  Mar.  1906.  (Sec'y  enrich.) 
Smyth,  Amer.  Jour.  Sci.,  XIX:  277,  1905.  (Pyrite  replacing  quartz.) 
Spurr,  Geology  Applied  to  Mining,  New  York,  1904.  Stokes,  Econ. 
Geol.,  July-Aug.,  1906.  (Sec'y  enrich.)  Sullivan,  Ibid.,  Oct. -Nov., 
1905.  (Ore  deposition.)  Weed,  Eng.  and  Min.  Jour.,  Feb.  23,  1905. 
(Absorption.)  Day  and  Eichards,  U.  S.  Geol.  Surv.,  Bull.  285.  (In- 
vestigation of  black  sands.) 

IRON  ORES 

Bowron,  Amer.  Inst.  Min.  Eng.,  Trans.  XXXVI :  587.  (Clinton  ore,  Ala.) 
Eckel,  U.  S.  Geol.  Surv.,  Bull.  285.  (Clinton  ore,  Ala.)  Eckel,  Ibid. 
(Oriskany  and  Clinton  ore,  Va.)  Holden,  Ibid.  (Virginia  limonites.) 
Kindle,  Ibid.  (Bath  Co.,  Kentucky.)  Leith,  Econ.  Geol.,  I,  No.  4 
(Iron  ore  reserves.)  Leith,  U.  S.  Geol.  Surv.,  Bull.  285.  (W.  United 
States.) 

COPPER  ORES 

Kemp,  Econ.  Geol.,  I.  (Sec'y  enrich.)  Beeler,Wyo.  Geol.  Surv.,  Sept. 
1,  1905.  (Grand  Encampment  dist.)  Fishburn,  Eng.  and  Min.  Jour., 
Sept.  22,  1906.  (Inyo  Co.,  Calif.)  Grant,  U.  S.  Geol.  Surv.,  Bull.  284. 
(Alaska.)  Lane,  Lake  Sup.  Min.  Inst.,  1906.  (L.  Sup.  dist.)  Law- 
son,  Bull.  Dept.  Geol.  Univ.  Calif.,  IV:  287.  (Robinson  dist.,  Nev.) 
Lindgren,  U.  S.  Geol.  Surv. ,  Prof.  Paper  43.  (Clifton-Morenci. )  Phalen, 
U.  S.  Geol.  Surv.,  Bull.  285.  (Luray,  Va.)  Root,  Min.  World,  Sept. 
29,  1906.  (Ely,  Nev.)  Weed,  U.  S.  Geol.  Surv.,  Bull.  285.  (U.  S. 
copper  deposits.)  Weed  and  Watson,  Econ.  Geol.,  I:  309.  (Virginia.) 


APPENDIX  II  433 


LEAD  AND  ZINC   ORES 

Bain,  U.  S.  Geol.  Surv.,  Bull.  246.  (N.  W.  Illinois.)  Bain,  Min.  Mag., 
July,  1905.  (Soft  lead  resources,  U.S.)  Buckley  and  Buehler,  Mo. 
Geol.  Surv.,  2d  ser.,  IV.  (Granby  area,  Mo.)  Bain,  U.  S.  Geol. 
Surv.,  Bull.  285.  (Nevada  zinc.)  Brinsmade,  Mines  and  Min.,  Sept., 
1906.  (Kelly,  N.  Mex.)  Grant,  Wis.  Geol.  and  Nat.  Hist.  Surv.,  Bull. 
14.  (Wisconsin.)  Miller,  Ky.  Geol.  Surv.,  Bull.  2.  (C.  Kentucky.) 
Siebenthal,  Econ.  Geol.,  1 :  119.  (Joplin  district,  Mo.)  Ulrich  and 
Smith,  U.  S.  Geol.  Surv.,  Prof.  Paper  36.  (W.  Kentucky.)  Watson, 
Amer.  Inst.  Min.  Engrs.,  XXXV :  681.  (Va.-Tenn.  area.) 

GOLD  AND  SILVER 

GENERAL.  Lovewell,  Trans.  Kan.  Acad.  Sci.,  XX,  Pt.  1  :  205.  (Genesis 
placer  and  vein  gold.)  Smyth,  Eng.  and  Min.  Jour.,  June  29,  1905. 
(Placers,  origin,  and  class'n.)  De  Launay,  Rev.  gen.  d.  Sci.,  June  15 
and  30,  1906.  (Gold  occurrence  and  production  in  world.) 

AKEAL.  —  Alaska:  Papers  by  various  authors  in  U.  S.  Geol.  Surv.,  Bulls. 
277,  284,  247,  280,  251,  and  287.  — Arizona  :  Kellogg,  Econ.  Geol.,  July- 
Aug.,  1906.  (Cochise  Co.)  Crosby,  Amer.  Inst.  Min.  Engrs.,  Trans. 
XXXVI:  626.  (Washington  Camp.) — California:  Bateson,  Amer. 
Inst.  Min.  Engrs.,  Bimonthly  Bull.,  Jan.,  1906.  (Mojave  dist.)  Diller, 
U.  S.  Geol.  Surv.,  Bull.  260:  45.  (Indian  Valley  region.)  Ball,  U.  S. 
Geol.  Surv.,  Bull.  285.  (S.  W.  Nev.  and  E.  Calif.)  — Colorado :  Spurr 
and  Garrey,  Ibid.  (Idaho  Springs.)  Wolff,  Min.  World,  Dec.  16, 1905. 
(Boulder  Co.)  Gale,  U.  S.  Geol.  Surv.,  Bull.  285.  (Hahn's  Peak.) — 
Idaho:  Collier,  Ibid.  (St.  Joe  River  basin.)  — Montana:  Douglass, 
Mines  and  Min.,  Feb.  1905.  (Alder  Gulch. )— Nevada :  Ball,  U.  S. 
Geol.  Surv.,  Bull.  285.  (S.  W.  Nev.  and  E.  Calif.)  Hastings,  Amer. 
Inst.  Min.  Engrs.,  Trans.  XXXVI.  (Silver  Peak.)  Hastings  and 
Berkey,  Amer.  Inst.  Min.  Engrs.,  Bimonthly  Bull.,  March,  1906.  (Gold- 
field.)  Pack,  Sen.  of  M.  Quart.,  April  and  July,  1906.  (Pioche.) 
Reid,  Bull.  Dept.  Geol.  Univers.  Calif.,  IV:  177.  (Comstock  Lode.) 
Rice,  Eng.  and  Min.  Jour.,  Sept.  22,  1906.  (Bullfrog  district.)  Spurr, 
U.  S.  Geol.  Surv.,  Prof.  Paper  55.  (Silver  Peak.)  Spurr,  Amer.  Inst. 
Min.  Engrs.,  Trans.  XXXVI :  372.  (W.  Nevada  ores.)  —New  Mexico  : 
Lindgren  and  Graton,  U.  S.  Geol.  Surv.,  Bull.  285. 

MERCURY 

Phillips,  Econ.  Geol.,  I,  No.  2.  (Texas.)  Stovall,  Min.  World,  Aug.  25, 
1906.  (Oregon.)  Turner,  Econ.  Geol.,  I,  No.  3.  (Texas.) 

NICKEL,   COBALT 

Coleman,  Ont.  Bur.  Mines,  XIV,  Ann.  Rept.,  Pt.  III.    (Sudbury  nickel 
field.)     Miller,  Ibid.,  Pt.  II.     (Cobalt-nickel  deposits,  Temiskaming. ) 
2r 


434  APPENDIX  II 


TIN 

Hess,  U.  S.  Geol.  Surv.,  Bull.  284.    (Alaska.)    Eichardson,  Ibid.,  Bull.  285. 
(Texas.) 

TUNGSTEN 

Joseph,  Eng.  and  Min.  Jour.,  March  3,  1906.     (Washington.)     Van  Wag 
enen,  Colo.  Sen.  of  M.  Bull.,  Jan.,  1906.     (Colorado  and  general.) 


INDEX 


Abrasives,  168. 
artificial,  165. 
production  of,  165. 
references  on,  166. 

See  Buhrstones,  Whetstones,  Pumice,  Co- 
rundum, Garnet,  Quartz,  Infusorial 
Earth. 

Actinolite,  as  gangue  mineral,  295. 
Adobe  clay,  defined,  99. 
uEolian  soils,  214. 

Alabama,  bauxite,  876  ;  clinton  ore,  266 ;  fuller's 
earth,  175 ;  graphite,  179  ;  kaolin,  101 ; 
limonite,  271 ;  phosphate,  158  ;  Port- 
land cement  materials,  119 ;  stoneware 
clay,  108  ;  Warrior  coal,  analysis,  7. 
Alabaster,  143. 

Alaska,  coal,  82 ;  coal  mining,  83  ;  copper,  298 ; 
gold,  353  ;  lignite,  analysis  from,  6  ; 
magmatically  segregated  ores,  225; 
petroleum,  54  ;  tin,  412  ;  yield  of  gold 
ores,  832. 
Albertite,  properties,  59. 

distribution,  59. 
Algeria,  onyx  marbles,  83. 
Algonkian,  copper  in,  295 ;  Iron  in,  260. 
Alkali  soils,  215. 
Alkalies,  effect  on  clay,  96. 
Alluvial  soils,  214. 
Almandite,  uses  as  gem,  194. 
Alumina,  effect  on  clay,  95. 
in  iron  ores,  252. 
in  soils,  214. 
Aluminum,  375. 

for  lithographic  work,  182. 
ores  of,  375. 
production  of,  882. 
references  on,  888. 
uses  of,  879. 
Alundum,  165. 
Amethyst,  as  gem,  195. 
Amorphous  phosphates,  see  Phosphates. 
Amygdaloids,  copper-bearing,  288. 
Analyses  of,  anthracite   coal,  8;   asphaltites, 
60 ;  bauxite,  376 ;  bituminous  coal,  8 ; 
bituminous  rocks,  61 ;  cement  rock, 
natural,  112 ;  chromite,  400 ;  clays,  98 ; 
coal,   elementary,   14 ;   copper   ores, 
Butte,  285;  fuller's  earth,  175;  glass 
sand,  177 ;  greensand,  156 ;  gypsum, 
148;    hematites,    364,    268;     kaolin, 


crude,  101 ;  kaolin,  washed,  101 ;  lig- 
nite, elementary,  14 ;  limestones,  109  ; 
limonites,  272;  lithographic  stone, 
181 ;  magnetites,  uon-titaniferous, 
257;  magnetites,  titaniferous,  258; 
maltha,  60 ;  mine  waters,  227 ;  min- 
eral waters,  206;  monazite,  191; 
natural  gas,  48 ;  peat,  elementary, 
14 ;  petroleum,  41 ;  phosphates,  154 ; 
Portland  cement  materials,  115 ;  Port- 
land cements,  116;  proximate,  of 
United  States  coals,  6;  rock  salt, 
181;  solid  matter  in  brine,  181; 
waters,  sea  and  ocean,  124. 
Analysis  of,  barite,  170;  bat  guano,  155  ;  bitu- 
minous coal  ash,  9  ;  brick  clay,  98  ; 
calcareous  clay,  98  ;  copper  ore,  298 ; 
fire  clay,  98 ;  graphite,  178  ;  gypsum, 
calcined,  144 ;  kaolin,  98  ;  kaollnite, 
98 ;  lignite  ash,  9 ;  molding  sand,  189 ; 
nickel  ore,  Canada,  405 ;  oil  shale,  57  ; 
peat  ash,  9;  pyrite,  199;  shale,  98; 
stoneware  clay,  98 ;  tungsten  concen- 
trates, 415;  zinc  ore,  315;  zinc  ore, 
Creede,  Colo.,  819 ;  zinc  ore,  Lead- 
ville,  818;  zinc  ore,  New  Jersey, 

Anglesite,  308,  305,  871. 
Anhydrite,  defined,  189. 
Anthracite,  5,  22. 

effect  of  igneous  intrusions  on,  15. 

price  per  ton,  84. 

properties  of,  5. 

Anthraxolite,  occurrence  and  properties,  59. 
Antimony,  896. 

distribution  in  United  States,  896. 

gangue  minerals,  396. 

mode  of  occurrence,  896. 

production,  897. 

references  on,  897. 

sources,  896. 

uses,  397. 

with  mercury,  893. 
Apatite,  as  a  fertilizer,  14T. 

sources,  147. 
Apex,  289. 
Appalachian  coal  field,  20. 

anthracite  area,  22. 

bituminous  area,  21. 

character  of  bituminous  coals,  22. 
Appalachian  petroleum,  distillates  from,  42. 


435 


436 


INDEX 


Appalachian  region,  copper  ores  of,  294. 
depth  of  oxidation  in  ore  bodies,  244. 
petroleum  in,  48. 
Apsdin,  Joseph,  discoverer  of  Portland  cement, 

118. 

Aquamarine,  194. 
Archaean,  Iron  ores  in,  261. 
Argentite,  286,  826. 

Argillaceous  limestone,for  Portland  cement,114. 
Arizona,  asbestos,  168 ;  fluorspar,  173  ;  garnet, 
195;  molybdenum,  403;  rubies  (so 
called),  193 ;  tungsten,  415  ;  turquoise, 
194;  vanadium,  416;  weathering  of 
ores,  281. 

Arkansas,  bauxite  In,  378;  bituminous  coal, 
analysis  of,  7 ;  coal  fields,  29  ;  fuller's 
earth,  175  ;  lignite,  30  ;  llmonite,  271 ; 
manganese,  887;  novaculite,  160; 
phosphate,  158  ;  Portland  cement  ma- 
terials, 119;  semi-bituminous  coal, 
analysis  of,  7 ;  whetstone,  160 ;  zinc 
ores,  815. 

Arkose,  defined,  85. 
Arsenic,  898. 

distribution.Virginia,  898 ;  Washington,  398. 
in  iron  ores,  252. 
references  on,  898. 
sources  of,  898. 
uses,  898. 
with  mercury,  893. 
Arsenopyrite,  898. 
Artesian  water,  209. 

depth  below  surface,  209. 
distinction  from  ground  water,  210. 
distribution,    Atlantic    coast,    210;    Great 

Plains,  211 ;  Mississippi  Valley,  211. 
geologic  horizon  of,  209. 
in  metamorphlc  rocks,  210. 
Asbestos,  asbestos  minerals,  167. 

amphibole,  mode  of  occurrence,  167. 

as  mineral  pigment,  188. 

chrysotile  veins,  origin,  168. 

distribution,  167 ;  Canada,  168 ;  Georgia,  167 ; 

North  Carolina,  167  ;  Virginia,  167. 
production,  169. 
references  on,  169. 
serpentine,  mode  of  occurrence,  167. 
uses,  169. 

Ashburner,  on  origin  of  petroleum,  44. 
Ash,  coal,  analyses  of,  9. 
Ash  in  coal,  9. 
Ash  soils,  214. 

Ash,  volcanic,  see  Volcanic  Ash. 
Asia  Minor,  turquoise  in,  194. 
Aspen,  Colo.,  lead-silver,  807,  367. 
Asphaltites,  defined,  57. 
properties,  58. 
uses  of,  61. 

Asphaltum,  references  on,  67. 
Astral  oil,  56. 

Atlantic  Ocean,  analysis  of  water,  124. 
Azurite,  278,  281,  291,  293,  871. 


Babbitt  metal,  897. 

Bain,  on  Missouri  lead-zinc  ores,  817. 

Ball  clay,  defined,  99. 

distribution  of,  108. 
Barite,  as  mineral  pigment,  187. 

distribution,   170;  Connecticut,    170;  Mis- 
souri,    170;    North    Carolina,    170; 
Pennsylvania,  170  ;  Tennessee,  170; 
Virginia,  170. 
mode  of  occurrence,  170. 
production,  170. 
references  on,  171. 
uses,  170. 

Barre,  Vermont  granite,  77. 
Bauxite,  analyses  of,  876. 

distribution,  Alabama,  376  ;  Arkansas,  375 ; 

Georgia,  376 ;  New  Mexico,  879. 
production  of,  880. 
properties,  375. 


Bavaria,  lithographic  stone,  182. 

Beaufort,  8.  C.,  phosphate  deposits,  150. 

Beaumont,  Texas,  petroleum,  51. 

Becker,  on  mercury  origin,  393. 

Bedding  planes,  effect  on  quarrying,  74. 

Belgium,  buhrstones  from,  161. 

Benzine,  in  petroleum,  42. 

Berea  sandstone,  86. 

Bessemer  ores,  defined,  252. 

Bingham  Canyon,  Utah,  copper,  296,  807. 

Bisbee,  Ariz.,  copper,  290. 

Bismite,  899. 

Bismuth,  distribution,  Colorado,  399. 


production,  899. 


Bismuthinite,  899. 

Bismutite,  399. 

Bitumen,  with  mercury,  390,  893. 

with  zinc,  315. 
Bituminous  coal,  price  per  ton,  34. 

properties  of,  4. 

See  Coal. 
Bituminous  rocks,  analyses,  61. 

California,  described,  60. 

defined,  57. 

distribution,  geographic,  57. 
geologic,  57. 

Indian  Territory,  mentioned,  60. 

Kentucky,  mentioned,  60. 

origin,  57. 

Black  copper,  at  base  of  gossan,  244. 
Black  Hills,  S.  Dak.,  tin,  411. 

tungsten,  415. 

Black  Sea,  analysis  of  water,  124. 
Black  silver,  825. 
Blende,  as  contact  ore,  235. 

See  Sphalerite. 
Blnestone,  defined,  85. 

See  Building  stones. 


INDEX 


437 


Bonanzas,  237,  286,  888,  845. 
Bone  coal,  24. 
Boracite,  134. 
Borax,  184. 

marshes,  California,  185. 

minerals  containing,  184. 

near  Daggett,  185. 

production,  136. 

references  on,  185. 

uses,  185. 
Bornite,  278,  279,  286,  292. 

as  contact  ore,  235. 

secondary,  286. 
Bort,  192. 

Boulder,  Colo.,  petroleum  at,  53. 
Boulder,  Mont.,  auriferous  hot  spring,  228. 
Bradford  district,  Pa.,  natural  gas  in,  54. 
Brass,  299,  820. 
Braunite,  383. 
Brazil,    emerald,    198 ;    magnetite  sand,  258 ; 

monazite,  190;  topaz,  194. 
Breaker,  coal,  24. 
Brick  clay,  analysis  of,  98. 

defined,  99. 

distribution  of,  104. 
Brines,  natural,  127. 
Britannia  metal,  897. 
Brittle  silver,  325. 
Bromyrite,  325. 
Bronze,  299. 

Brooks,  on  Lake  Superior  ores,  262. 
Brownstone,  defined,  85. 
Buhrstones,  characters,  161. 

distribution,  161. 

German,  161. 
Building  stones,  69. 

absorption  of,  78. 

color,  70. 

crushing  strength,  72. 

cut  off,  74. 

density,  70. 

distribution,  gee  under  Granite,  Sandstone, 
Limestone,  Marble,  Slat*. 

fading,  cause  of,  70. 

hardness,  71. 

lift,  74. 

permanent  swelling,  78. 

porosity  of,  78. 

production  of,  89. 

properties  of,  69. 

quarry  water  in,  78. 

references  on,  90. 

resistance  to  frost,  73. 
to  heat,  78. 

rift,  74. 

sap  of,  78. 

specific  gravity,  71. 

strength,  71. 

texture,  70. 

Bully  Hill,  Calif.,  copper,  298. 
Butte,  Mont.,  copper  ores,  282. 

metasomatism  at,  284. 


Calamine,  303,  305,  810,  81». 
Calaverite,  339. 

Calcareous  clay,  analysis  of,  98. 
Calcite,  see  Gangue  minerals. 
California,  asbestos  mentioned,  168;  coal,  31, 
82 ;  copper,  297 ;  fire  clay,  108 ;  infu- 
sorial earth,   mentioned,  162;  Kern 
Kiver  oil  field,  58;  lignite,  analysis, 
1 ;  lithium,  183  ;  magnesite,  184  ;  mag- 
netite, 256 ;  manganese,  887 ;  marble, 
82 ;  mercury,  891 ;  molybdenum,  403  ; 
natural  gas,  56 ;  petroleum,  52 ;  petro- 
leum, characters,  58  ;  platinum,  408 ; 
Portland  cement  materials,  119  ;  salt, 
180;  stoneware  clay,  108;  topaz,  194. 
Californite,  as  gem,  195. 
Calomel,  390,  391. 
Calumet  conglomerate,  288. 
Cambrian,  glass  sand,  177. 
gold  ores,  329. 
ocher,  187. 
silver  ores,  829. 
tungsten,  415. 
Cambro-Silurian  limonite,  271. 

pyrite,  199. 

Cannel  coal,  properties  of,  5. 
Cape  Nome,  Alaska,  357. 
Carbonado,  192. 

Carboniferous,  Appalachian  section,  21 ;   tee 
Coal,  Anthracite,  distribution  ;  cop- 
per,  290,   293,   296;  gold   ores,   886; 
gypsum,    140;  hematite,  268;  lime- 
stones  for    Portland    cement,    119; 
petroleum,  53;  salt,  129;  shales  for 
Portland  cement,  119  ;  siderite,  273  ; 
silver  ores,  336 ;  silver-lead,  865,  867, 
870;  zinc  ores,  314,  819. 
Carbonite,  25. 
Carborundum,  165. 
Carters ville,  Ga.,  manganese,  386. 
Cassiterite,  410. 
Cat's  eye  (oriental),  194. 
Cavities,  depth  of  occurrence,  229. 
fault,  28. 

formation  of,  281. 
in  earth's  crust,  229. 
shrinkage,  281. 
solution.  231. 
Cement,  calcareous,  109. 
hydraulic,  defined,  111. 
natural,  analyses,  118. 

difference  from  Portland,  118. 
properties  of,  112. 
Portland,  analyses  of,  116. 
properties,  118. 
raw  materials,  114. 
pozzuolano,  defined,  111. 

composition,  111. 
production,  120. 
references,  121. 
Roman,  112. 


438 


INDEX 


Cement  —  continued. 
Kosendale,  defined,  112. 
uses  of,  119. 

Cement  materials,  natural  rock,  Appalachian 
region,  117 ;  Illinois,  118  ;  Kentucky, 
118;  Maryland,  117 ;  New  Tork,  117 ; 
Ohio,  117;  Pennsylvania,  117;  Wis- 
consin, 118. 

Portland,   Alabama,  119;    Arkansas,   119; 
California,  119 ;  Colorado,  119  ;  Indi- 
ana,   119;    Kansas,    119;   Michigan, 
119;  New  Jersey,  118;  New  Tork, 
118 ;  North  Dakota,  119  ;  Ohio,  119  ; 
Pennsylvania,    118;    South   Dakota, 
119 ;  Texas,  119 ;  Utah,  119. 
geologic  age,  118. 
Cement  plaster,  144^ 
Cement  rock,  natural,  analyses,  112. 
Cerargyrite,  825,  336. 
Cerium,  in  monazite,  191. 
Cerussite,  303,  305,  311,  871. 
Ceylon,  graphite  from,  179. 

topaz  in,  194. 
Chalcocite,  278,  281,  285,  286,  291,  292,  297, 

298. 

Chalcocite,  secondary,  286. 
Chalcopyrite,  278,  279,  281,  292,  293,  294. 
as  a  contact  ore,  235. 
in  pyrite  deposits,  199. 
Chalk,  80. 

Champion  Springs,  N.Y.,  205. 
Chara,  as  aid  in  marl  formation,  119. 
Chester,  Mass.,  emery  deposits,  164. 
China  clay,  defined,  99. 
Chlorastrolite,  as  gem,  195. 
Chlorine,  in  soils,  214. 
Chlorite,  826. 

Chrome  yellow,  as  mineral  pigment,  188. 
Chromic  iron,  399. 
Chromite,  399. 
analyses,  400. 
as  mineral  pigment,  188. 
associated  rocks,  399. 
association  with  peridotite,  226. 
distribution  in  United  States,  400;    Cali- 
fornia,   401;    North   Carolina,    401; 
Pennsylvania,  401. 
origin  of,  400. 
production  of,  402. 
references  on,  402. 
uses  of,  401. 
with  platinum,  408. 
Chrysocolla,  278,  281. 
Chrysoprase,  as  gem,  195. 
Chrysotlle,  167. 
Chrysotile  reins,  origin,  168. 
Cinnabar,  890,  393. 
Cinnabar,  as  mineral  pigment,  188. 
Classification  of,  clays,  98. 

ore  deposits,  246. 
Clay,  adobe,  defined,  99. 


air  shrinkage,  96. 

alkalies  in,  96. 

alumina  in,  95. 

analyses  of,  98. 

ball,  distribution  of,  103. 

classification  of,  98. 

defined,  92. 

distribution,  by  kinds,  100, 

fire,  distribution  of,  104. 

fire  shrinkage,  97. 

flood-plain,  94. 

fusibility  of,  97. 

geologic  distribution,  100. 

glacial,  94. 

glass  pots,  sources,  104. 

iron  oxide  in,  95. 

kaolin,  defined,  99,  100. 

lake,  94,  104. 

lime  in,  96. 

magnesia  in,  96. 

marine,  94. 

miscellaneous,  referred  to,  104. 

origin,  92,  98. 

paper,  sources,  104. 

physical  properties,  96. 

plasticity  of,  96. 

pottery,  99,  103. 

products,  production  of,  105. 

properties  of,  95. 

references  on,  106. 

residual,  104. 

sedimentary,  98. 

silica  in,  95. 

specific  gravity,  97. 

stoneware,  distribution  of,  103. 

sulphur  trioxide  in,  96. 

tensile  strength,  96. 

titanic  acid  in,  96. 

uses  of,  105. 

varieties,  99. 

water  in,  96. 

Clay  soils,  properties,  215. 
Clausthal,  Prussia,  banded  veins  at,  287. 
Clifton,  Ariz.,  copper,  293. 
Clinton  limestone,  gas  in,  55. 
Clinton  ore,  266. 

analyses,  268. 

Birmingham,  Ala.,  266. 

character,  266. 

distribution,  266. 

origin,  267. 
Coal,  8. 

age  of,  19. 

anthracite,  defined,  5. 

bituminous,  defined,  4. 

bone,  24. 

onnnel,  defined,  5. 

Carboniferous,  distribution,  19. 

cretaceous,  distribution,  19. 

distribution,  Alabama,  20;  Alaska,  82; 
Appalachian  field,  20;  Arkansas.  28, 
80;  California,  82;  Colorado,  81; 


INDEX 


439 


Coal,  distribution  —  continued. 

Dakota,  31 ;  Eastern  Interior  field,  26 ; 
Illinois,  27  ;  Indiana,  27  ;  Indian  Ter- 
ritory, 29;  Iowa,  29;  Kansas,  29; 
Kentucky,  27;  Maryland,  22;  Michi- 
gan, 27 ;  Montana,  31 ;  New  Mexico, 
81 ;  Northern  Interior  field,  27  ;  Ore- 
gon, 82 ;  Pacific  coast  field,  31 ;  Penn- 
sylvania, 22;  Rhode  Island  field,  25; 
Eocky  Mountain  field,  80;  South 
Dakota,  31 ;  Southwestern  field,  29  ; 
Texas,  30  ;  Triassic  area,  25 ;  United 
States,  18 ;  Washington,  32 ;  Western 
Interior  field,  29. 
elementary  analysis,  14. 
faulting,  18. 

formation  of,  chemical  changes  during,  12. 
geologic  distribution  in  United  States,  19. 
heat  and  pressure,  effect  on,  14. 
kinds  of,  8. 
origin  of,  9. 
outcrops,  15. 
price  per  ton,  84. 
production  of,  88. 

proximate  analysis  of,  explained,  6. 
proximate  analyses  of  United  States  coals,  6. 
references  on,  35. 
rocks  associated  with,  16. 
seams,  see  Coal  beds, 
semi-bituminous,  defined,  5. 
Triassic,  distribution,  19. 
Coal  beds,  pinching  of,  16. 
splitting  of,  17. 
structural  features,  15. 
swelling  of,  16. 
thickness  of,  16. 
Coal-blossom,  16. 
Coal-brasses,  200. 
Coal-breaker,  24. 
Cobalt,  Missouri,  404. 
ores,  404. 

production  of,  406. 
references  on,  407. 
uses,  406. 

Cobaltite,  as  mineral  pigment,  188. 
Coke,  natural,  see  Carbonite. 

production  of,  85. 
Colemanite,  184. 

Colorado,  anthracite  coal,  analysis  of,  8 ;  coal, 
31 ;  coking  coal,  analysis  of,  7 ;  cop- 
per. 298  ;  desilverized  lead,  807  ;  fire 
clay,  103 ;  lignite,  analysis,  6 ;  limon- 
ite,  271 ;  magnetite,  256  ;  manganese, 
888 ;  petroleum,  53  ;  Portland  cement 
materials,  119  ;  stoneware  clay,  108 ; 
topaz,194;  tungsten,415;  uranium,416. 
Comb  structure,  287. 
Comstock  lode,  Nevada,  844. 
Conglomerate,  copper-bearing,  288. 
Connecticut,  barite,  170 ;  garnet,  163 ;  kaolin, 
101 ;  lithium  minerals,  188  ;  tungsten 
in,  415. 


Contact  deposits,  copper  ores,  298,  279. 

examples  of,  285. 

Contemporaneous    ores,    in    igneous    rocks, 
224. 

in  sedimentary  rocks,  225. 
Copper,  278. 

in  hot  spring  deposit,  228. 

in  iron  ores,  252. 

mode   of   occurrence    In    United    States, 
279. 

native,  278,  279,  287,  289,  296. 

ores  of,  278. 

production,  299. 

references  on,  801. 


with  mercury,  898. 
Copper  ore,  analysis,  California,  298. 
analyses  of,  Montana,  285. 
distribution,   281;    Alaska,    298;    Appala- 
chian  region,  294 ;  Ariz.,  290 ;  Bis- 
bee,    Ariz.,    290;     California,    297; 
Clifton,  Ariz.,   293;    Colorado,   298; 
Connecticut,  296;  Globe,  Ariz.,  294; 
Idaho,   298;    Jerome   district,    292; 
Michigan,  287 ;  Montana,  282 ;  New- 
Jersey,    296;     New    Mexico,    298; 
Pennsylvania,  296;  Utah,  296  ;  Wyo- 
ming, 298. 

Copper  ores,  gold  and  silver  bearing,  828. 
impurities,  280. 
superficial  alteration,  280. 
Coquina,  80. 

Corniferous  limestone,  gas  in,  55. 
Cornwall,  England,  tin  veins,  285. 
Cornwall,  Pa.,  magnetite,  256. 
Corsicana,  Texas,  petroleum,  52. 
Corundum,  ore  of  aluminum,  875. 
as  abrasive,  163. 
distribution,  168. 
Georgia,  164. 
North  Carolina,  164. 
mechanical  concentration,  165. 
origin,  164. 

Cottonwood  district,  Utah,  SOT. 
Covellite,  285,  286. 

carrying  platinum,  408. 
Creede,  Colo.,  807. 
Crested  Butte,  Colo.,  15. 
Cretaceous,  glass  sand  in,  176;  greensand  In, 
155 ;  lignite,  19 ;  limestone  for  lime, 
116;  mercury,  892;  petroleum,  58; 
phosphate,  158;   shale  for  Portland 
cement,  119. 

Crimora,  Va.,  manganese,  885. 
Cripple  Creek,  Colo.,  gold,  388. 
Crustification,  defined,  286. 
Cryolite,  875. 

Crystal  Falls  district,  hematite,  261. 
Culm,  defined,  24. 

uses,  24. 

Cuprite,  278,  291. 
Cut-off,  in  quarries,  74. 


440 


INDEX 


Dakota,  lignite  In,  81. 
Dead  Sea,  analysis  of  water,  124. 
Descension  theory,  240. 
Devonian,  phosphate  in,  153. 
Diamond,  properties  of,  192. 

South  Africa,  192. 

United  States,  192. 
Didymium  in  inonazite,  191. 
Dismal  Swamp,  analysis  of  peat  from,  6. 
Disseminated  ores,  242. 
Dolomite,  see  Gangue. 

defined,  78. 

petroleum  in,  51. 
Douglas  Island,  Alaska,, 864. 
Dredging  gold,  848. 
Drift  mining,  gold,  847. 
Duck  Elver,  Tenn.,  phosphate  deposits,  151. 
Ducktown,  Tenn.,  copper  at,  295. 
Dune  soils,  214. 


Eagle  Pass,  Texas,  coal,  80. 
Earthenware  clay,  defined,  99. 
Earth's  crust,  zones  in,  228. 
Eldridge,  on  Florida  phosphate,  149. 
Embolite,  825. 

Emerald,  distribution,  Brazil,  194 ;  Ceylon,  198 ; 
Hindostan,  193;  North  Carolina,  198; 
Siberia,  193. 

lithia,  194. 

properties,  198. 
Emery,  defined,  168. 

Massachusetts,  described,  164. 

New  York,  mentioned,  164. 
Emmons,  cited,  280. 
Enargite,  278,  279,  284,  872. 
England,  fuller's  earth  in,  175. 
Epidote,  295,  826. 

in  contact  deposits,  235. 


Faults,  effect  on  oil  reservoir,  58. 

relation  to  oil  springs,  58. 
Feather  Eiver,  Calif.,  gold  in,  849. 
Ferric  sulphate,  as  a  solvent  of  ores,  244. 

effect  on  pyrite,  244. 
Ferro-chromium,  401. 
Ferro-nickel,  401. 
Ferro-titanium,  414. 
Fertilizers,  apatite,  147. 

listed,  147. 

production  of,  156. 

references  on,  157. 

See     Phosphate,    Guano,    Gypsum,    and 

Greensand. 

Findlay,  Ohio,  oil  pressure  at,  45. 
Fire  clay,  analysis  of,  98. 

defined,  99. 

distribution  in  United  States,  102. 

under  coal,  16. 


Fissure  veins,  apex,  239. 

bonanzas,  237. 

boundaries  of,  236. 

comb  structure,  237. 

filling  of,  240. 

foot  wall,  239. 

hanging  wall,  289. 

linked,  239. 

lode,  239. 

ores  common  in,  237. 

secondary  banding,  286. 

selvage  in,  237. 

strike  of,  239. 

Fixed  carbon,  effect  of,  in  coal,  8. 
Flagstone,  defined,  85. 
Flats,  312. 

Flint  clay,  defined,  99. 
Florence  oil  field,  Colorado,  58. 
Florida,  ball  clay,  103 ;  phosphate,  148 ;  phos- 
phate, uses,  154. 
Fluorspar,  characters,  171. 

distribution,  Arizona,  173  ;  Illinois,  deposits 
described,  172 ;  Kentucky,  178 ;  Ten- 
nessee, 173. 

gangue  mineral,  172. 

gems,  195. 

occurrence,  171. 

origin,  178. 

production,  178. 

references  on,  178. 

uses,  178. 
Foot  wall,  239. 

Fort  Dodge,  Iowa,  gypsum  at,  140. 
Foster,  on  Lake  Superior  ores,  262. 
Fountain  head,  209. 
France,  buhrstones,  161. 
Franklinite,  303,  804,  SOS,  810. 
Fredonia,  N.T.,  gas,  40. 
Freestone,  defined,  85. 
Freiberg,  Saxony,  banded  veins  at,  237. 
Fuel  ratio,  8. 
Fuller's  earth,  analyses  of,  175. 

difference  from  clay,  174. 

distribution,  Alabama,  175;  Arkansas,  175; 
England,  175;  Florida,  175;  Ne- 
braska, 175;  New  York,  175;  South 
Dakota,  175. 

geological  distribution,  175. 

production  of,  176. 

properties,  174. 

references  on,  176. 


Gaffney,  S.C.,  tin,  411. 
Galena,  as  a  contact  ore,  285. 

mentioned,  803,  305,  306,  811,  812,  818,  815, 

329,  365,  870,871,  372,  878,  412. 
Galicia,  ozokerite  in,  59. 
Galvanic  action,  ore  precipitation  by,  285. 
Gangue  minerals,  barite,  811,  315,  336, 842,  365, 

867,  872. 
Cftloite,  811,  812,  815,  842,  865,  390,  893,  396. 


INDEX 


441 


jQaugue  minerals  —  continued. 
chert,  315,  365. 

dolomite,  811,  815,  339,  342,  367. 
epidote,  295,  412. 
fluorite,  311,  839,  410,  412. 
garnet,  295. 
lepidolite,  410. 
marcasite,  312,  818. 
muscovite,  410. 
orthoclase,  839,  844. 
quartz,  811,  885,  836,  339,  342,  844,  867,  370, 

872,  873,  390,  896,  412. 
rhodochrosite,  842,  370,  883. 
topaz,  410,  412. 
zinnwaldite,  412. 
Garnet,  as  an  abrasive,  163. 
as  a  gem,  194. 

distribution,  Arizona,  195 ;  Connecticut, 
mentioned,  163;  India,  194;  New 
Mexico,  195 ;  New  York,  mentioned, 
168  ;  North  Carolina,  195 ;  Tennessee, 
163. 

In  contact  deposits,  235. 
uses  as  abrasive,  163. 
Gash  veins,  in  Wisconsin,  240. 

defined,  240. 

Gasoline,  in  petroleum,  42. 
Genthite,  404. 

Georgia,  asbestos,  167 ;  bauxite,  376 ;  corun- 
dum, 164  ;  graphite,  179  ;  manganese, 
886;    ocher,    187;    phosphate,    154; 
stoneware  clay,  103. 
German  silver,  321. 
Germany,  buhrstones  from,  161. 
Gibbsite,  875. 


analysis  of,  60. 

occurrence,  59. 

properties,  59. 
Glacial  soils,  214. 
Glass  sand,  analyses  of,  177. 

distribution,  Illinois,  177  ;  Iowa,  177 ;  Mary- 
land, 177;  Massachusetts,  177;  New 
Jersey,  177 ;  Pennsylvania,  177 ;  West 
Virginia,  177. 

effect  of  clay  in,  176. 

effect  of  iron  oxide  on,  176. 

geologic  distribution,  176. 

production,  177. 

properties,  176. 

references  on,  ITS. 
Glauber  salt,  136. 
Globe,  Ariz.,  copper,  294. 
Gold,  gravels,  346. 

gravels,  Pacific  Coast,  847. 
Gold  Hill,  N.C.,  copper  at,  295. 
Gold,  in  beach  sands,  849. 

native,  825,  836,  889,  865. 
Gold  ores,  chlorination  process,  880. 

classification,  327. 

cyanide  process,  830. 

distribution,  Alaska,   353;   Alaska,  placer 


deposits,  856;  Black  Hills,  850;  Crip- 
ple Creek,  Colo.,  888 ;  Cordilleran  re- 
gion, 332 ;  Homestake  belt,  8.  Dak., 
351 ;  Idaho,  887  ;  Mercur,  Utah,  836 ; 
Michigan,  852 ;  Montana,  887 ;  Mother 
Lode  belt,  Calif.,  838;  Nevada  Co., 
Calif.,  334;  Oregon,  885;  Pacific  coast 
belt,  332 ;  Washington,  835. 

eastern  crystalline  belt,  852. 

extraction,  829. 

free  milling,  defined,  829. 

geologic  distribution,  829. 

gold-milling  centres,  830. 

igneous  rocks  associated  with,  826. 

in  igneous  rocks,  826. 

in  metamorphic  rocks,  326. 

in  propylitic  veins,  826. 

listed,  825. 

mode  of  occurrence,  326. 

production  of,  858. 

quartzose,  328. 

quartz  veins,  826. 

references  on,  860. 

refractory,  defined,  829. 

sands  in  arid  region's,  849. 

secondary  enrichment  of,  327. 

siliceous,  Cambrian,  South  Dakota,  852. 

uses  of,  857. 

valuation  of,  830. 

wall  rocks,  826. 

weathering  of,  827. 

with  mercury,  893. 

with  platinum,  408. 

Gold-silver  ores,  distribution,  Bohemia  district, 
Ore.,  845;  Boulder  Co.,  Colo.,  845; 
Central  Belt,  335;  Clear  Creek  Co., 
Colo.,  845;  Comstock  lode,  Nev., 
844 ;  Eastern  Belt,  Tertiary  ores,  337 ; 
Gilpin  Co.,  Colo.,  845 ;  Monte  Cristo, 
Wash.,  345;  Ouray,  Colo.,  842;  Owy- 
hee  Co.,  Ido.,345;  San  Juan  region, 
Colo.,  841 ;  Silverton,  Colo.,  841 ;  Tel- 
luride,  Colo.,  842 ;  Tonopah,  843. 
Gold  veins,  associations  with  igneous  rock,  280. 
Gossan,  defined,  242. 

leaching  of,  244. 
Grahamite,  analysis  of,  60. 

occurrence,  59. 

Grand  Eapids,  Mich.,  gypsum  at,  142. 
Granites,  75. 

characteristics  of,  75. 

color  of,  75. 

distribution,  California,  77 ;  Central  States, 
77  ;  eastern  crystalline  belt,  77  ;  Min- 
nesota, 77;  Missouri,  77;  Montana, 
77;  Oregon,  77;  South  Dakota,  77; 
Texas,  77 ;  United  States,  77 ;  Wash- 
ington,  77 ;  western  states,  77. 

durability  of,  75. 

geologic  range,  76. 

uses  of,  77. 

weight  of,  75. 


442 


INDEX 


Graphite,  amorphous,  179. 

amorphous,  Khode  Island,  179. 
analysis,  178. 
artificial,  180. 
as  mineral  pigment,  188. 
distribution,   Alabama,  179;  Ceylon,  179; 
Ceylon,   origin,   179;    Georgia,   179; 
Michigan,  not  such,  179;  Montana, 
179;    New    Hampshire,    179;    New 
York,    179;    North    Carolina,    179; 
Pennsylvania,   179 ;    Wisconsin,   not 
such,  179. 
occurrence,  178. 
production,  180. 
properties  of,  178. 
references  on,  181. 
uses,  179. 

Grass  Valley,  Calif,  834. 
banded  veins  at,  287. 
Gravels,  auriferous,  846. 
Gravity  of  petroleum,  41. 
Great  gossan  lead,  295. 
Great  Salt  Lake,  analysis  of  water,  124. 
Greenland,  cryolite  in,  378. 
Greensand,  analyses,  156. 
defined,  155. 
distribution,  155. 
source  of  Texas  limonite,  271. 
Virginia,  uses  of,  155. 
Greisen,  tin  bearing,  410. 
.Grindstones,  distribution,  159. 

properties  of,  158. 
Ground  water,  208. 

movements  of,  208. 
Guano,  156. 
bat,  155. 

bat,  analysis,  156. 
bat,  Texas,  155. 
kinds,  155. 
Peru,  165. 
West  Indies,  165. 
Gumbo  clay,  defined,  99. 
Gypsite,  defined,  189. 

distribution,  Kansas,  141 ;  Oklahoma,  142 ; 

Texas,  142;  Wyoming,  142. 
origin  of,  140. 

Gypsum,  absence  from  Kansas  salt  beds,  130. 
analyses  before  and  after  calcination,  144. 
analyses  of,  148. 
as  mineral  pigment,  187. 
calcination  process,  144. 
composition,  139. 

distribution,  Arizona,  142  ;  California,  142  ; 
Colorado,  142  ;  Idaho,  142  ;  Iowa,  140 ; 
Kansas,  141 ;  Michigan,  142 ;  Mon- 
tana, 142  ;  Nevada,  142  ;  New  York, 
142 ;  Ohio,   142  ;  South  Dakota,  142 ; 
Vermont,  142  ;  Virginia,  142. 
formed  from  pyrite,  140. 
formed  from  sea-water,  140. 
geologic  distribution,  189. 
occurrence,  189. 


origin,  189. 
production  of,  145. 
references  on,  146. 
uses,  143. 
volcanic  origin  of,  140. 


Hamilton  shales,  for  Portland  cement,  118. 

Hanging  wall,  239. 

Hayes,  on  Arkansas  bauxite,  879. 

on  Georgia  bauxite,  876. 

on  Tennessee  phosphates,  158. 
Hematite,  259. 

analysis,  Lake  Superior,  264. 

as  mineral  pigment,  186. 

distribution,  Alabama,  268;  Lake  Superior 
region,  259;  Missouri,  269;  Utah, 
268;  Wyoming,  268;  United  States, 
259. 

in  contact  deposits,  285. 

with  mercury,  398. 

See  Clinton  ore. 

Hermann,  on  weight  of  stones,  71. 
Hindostan,  emerald  in,  193. 
Hindostan  stone,  160. 
Holston  Valley,  Va.,  gypsum,  142. 
Horn  silver,  325. 
Hot  spring,  gold-bearing,  228. 
Hot    spring   deposits,    see    Stibnite,   Pyrite, 

Copper. 

Hot  Springs,  204. 
Hubnerite,  414. 
Humus,  213. 
Hungary,  opal  in,  195. 
Huronian,  iron  ores  in,  261. 
Hydraulic  limes,  see  Lime. 
Hydraulic  mining,  348. 


Idaho,  auriferous  lead  ores  in,  829 ;  copper, 
298;  nickel,  405;  silver-lead  ores,  372. 

Idaho  basin,  Idaho,  337. 

Igneous  rocks,  miscellaneous,  for  building,  78. 

Illinois,  brick  clays,  104;  bituminous  coal, 
analysis  of,  7 ;  coal  field,  26 ;  glass 
sand,  177;  natural  rock  cement,  118; 
ocher,  187 ;  sienna,  187 ;  stoneware 
clay,  108. 

Ilmenite,  257,  418. 

India,  garnet  in,  194. 
source  of  mica,  186. 

Indiana,  Brazil  coal,  analysis  of,  7 ;  brick  clays, 
104 ;  cannel  coal,  analysis  of,  7 ;  coal 
field,  27  ;  petroleum,  distillates  from, 
42  ;  natural  gas,  55 ;  natural  gas  analy- 
sis, 48 ;  petroleum,  50 ;  Portland  ce- 
ment materials,  119  ;  stoneware  clay, 
103  ;  whetstones  mentioned,  160. 

Indian  Territory,  coal  field,  29;  natural  gas, 
55. 

Infusorial  earth,  defined,  162. 

distribution,  California,  162 ;  Maryland,  162 ; 


INDEX 


443 


Infusorial  earth,  distribution  —  continued. 

Missouri,  162;  Nevada,  162;  New 
England,  162 ;  New  York,  162 ;  Vir- 
ginia, 162. 

German  deposits,  162. 

uses,  162. 

Iowa,  bituminous  coal,  7;  coal  in,  29;  glass 
sand  in,  177  ;  gypsum,  140 ;  lime  rock 
in,  116 ;  limonite  in,  271 ;  lithographic 
stone  in,  182 ;  stoneware  clay  in,  103  ; 
zinc  ores  in,  311. 
Iridium,  properties  and  occurrence,  410. 

uses,  410. 

with  platinum,  407. 
Iron,  in  copper  ores,  280. 
Iron  Mountain,  Calif.,  copper,  298. 
Iron  ores,  distribution,  Alabama,  266,  271; 
Arkansas,  271 ;  California,  256 ;  Colo- 
rado, 256,  257 ;  Iowa,  271 ;  Kentucky, 
278 ;  Michigan,  256,  261,  265 ;  Minne- 
sota, 257,  261,  264,  271 ;  Missouri, 
269;  New  Jersey,  256,  257;  New 
Mexico,  256,  268;  New  Tork,  255, 
257,  258,  266,  273;  North  Carolina, 
255;  Ohio,  266,  273;  Oregon,  271; 
Pennsylvania,  256,  273;  Sweden,  270  ; 
Texas,  271;  Utah,  256,  268;  Ver- 
mont, 271 ;  Virginia,  271 ;  Wisconsin, 
261,  266,  271 ;  Wyoini 

distribution  in  United  States,  254. 

geologic  distribution,  254. 

impurities  in,  252. 

magnetite,  modes  of  occurrence,  254. 

magnetites,  origin  of,  256. 

modes  of  origin,  253. 

non-titaniferous,  254. 

production  of,  278. 

references  on,  276. 

See  Hematite  and  Limonite. 
Iron  oxide,  effect  on  clay,  95. 

in  soils,  214. 
Irving,  on  Lake  Superior  ores,  262. 


Japan,  solfataric  sulphur  in,  196. 
Jenney,  on  Missouri  lead  zinc  ores,  817. 
Jennings,  La.,  petroleum,  52. 
Jerome,  Ariz.,  copper,  292. 
Jet,  4. 

Joplin,  Mo.,  zinc  ores,  808,  314. 
Josephinite,  408. 

Jurassic,  gold,  333;  lithographic  stone, 
sulphur  in,  197. 


Kansas,  coal,  29 ;  gypsite,  141 ;  gypsum,  141 
lime  rock,  116 ;  natural  gas,  55 ;  petro 
leum,  52  ;  petroleum,  distillates  from 
42 ;  Portland  cement  materials,  119 
salt,  130. 

Kaolin,  denned,  99. 
analysis  of,  98, 101. 


distribution,   Alabama,    101;    Connecticut, 
101 ;  Maryland,  101 ;  North  Carolina, 
101;    Pennsylvania,    101;    Virginia, 
101. 
origin,  93. 

Kaolinite,  92. 
analysis  of,  98. 
product  of  metasomatism,  326. 

Kemp,  cited,  230,  246,  257,  810,  407. 

Kentucky,  ball  clay  in,  103;  bat  guano,  155; 
bituminous  coal,  analysis  of,  7 ;  coal 
field,  27  ;  fluorspar,  178  ;  lithographic 
stone,  182;  molding  sand,  190;  natu- 
ral gas,  56  ;  natural  rock  cement,  118  ; 
stoneware  clay,  103. 

Kerosene,  in  Wyoming  petroleum,  58. 

Kerosene  shale,  57. 

Keweenaw  series,  Michigan,  287. 

Klondike  Kiver,  Alaska,  854,  856. 

Knox  dolomite,  876. 

Kunzite,  as  gem,  195. 


Lake  asphalt,  59. 

Lake  Superior  ores,  259. 

analyses,  264. 

character,  260. 

development,  265. 

origin,  263. 

Lanthanum,  in  monazite,  191. 
Lateral  secretion  theory,  240. 
Lead,  desilverized,  occurrences,  807. 

gangue  minerals  of,  804. 

ores  of,  303. 

production  of,  821. 

references  on,  828. 

uses  of,  319. 

with  mercury,  898. 
Lead  ores,  Colorado,  307. 

disseminated,  306. 

distribution,  Appalachian  belt,  806;  Mis- 
souri,  806,  814;  Rocky  Mountain 
states,  818. 

gold  and  silver  bearing,  828. 

impurities  in,  804. 

modes  of  occurrence,  804. 

superficial  alteration,  805. 
Leadville,  Colo.,  364. 
Lepidolite,  183. 

Lesley,  on  origin  of  petroleum,  44. 
Lift,  in  quarries,  74. 
Lignite,  4. 

age  of,  4. 

areas  in  United  States,  19. 

Gulf  States  area,  30. 

properties  of,  4. 
Lime,  effect  on  clay,  96. 

effect  on  soils,  215. 

In  iron  ores,  252. 

properties,  110. 

references  on,  121. 

uses  of,  119. 


444 


INDEX 


JJmes,  hydraulic,  distribution,  117. 

properties  of,  112. 
Limestone,  analyses,  109. 

burning,  changes  in,  110. 

Cretaceous,  for  building,  80. 

distribution  in  United  States,  80. 

for  lime,  distribution,  116. 

for  Portland  cement,  114,  118. 

general  characteristics,  78. 

lithographic,  181. 

varieties,  78. 

See  Building  stones. 
Limonite,  269. 

advantage  of  using,  272. 

analyses  of,  272. 

bog  ores,  269. 

Cambro-Silurian,  271. 

distribution,  Appalachian,  271;  Arkansas, 
271 ;  Colorado,  271 ;  Iowa,  271 ;  Min- 
nesota, 271 ;  Oregon,  271 ;  Texas, 
271 ;  Wisconsin,  271. 

Great  Gossan  Lead,  271. 

manganiferous,  271. 

residual,  270. 

with  mercury,  393. 
Lindgren,  cited,  280. 

on  Colorado  gold  ores,  887. 
Linked  veins,  239. 
Linnaeite,  404. 
Lipari,  pumice  from,  162. 
Litharge,  819. 

Lithium,  distribution,  California,  188 ;  Connec- 
ticut, 183 ;  South  Dakota,  183. 

industry,  183. 

minerals  as  sources  of,  183. 

production,  183. 


Lithographic  stone,  analyses,  181. 

definition,  181. 

distribution,  Bavaria,  182  ;   Iowa,  182;  Ken- 
tucky, 182. 

physical  properties,  182. 

references  on,  183. 
Lithophone  paint,  170. 
Lode,  239. 
Loess,  defined,  99. 
Louisiana,  petroleum,  52;  salt,  129;  sulphur, 

197. 

Lower  Carboniferous,  fluorspar  in,  172. 
Lower  Helderberg,  limestone  for  lime,  116. 


Magmatic  segregation,  224. 

in  acid  rocks,  225. 

in  basic  rocks,  224. 

of  copper,  279. 

Magmatic  water,  effects  of,  280. 
Magnesia,  effect  on  clay,  96. 

in  iron  ores,  252. 

in  natural  cements,  113. 

in  soils,  214. 


Magnesite,  California,  184. 

occurrence  and  properties,  188. 

production,  184. 

references  on,  184. 

uses,  184. 
Magnetite,  as  a  contact  ore,  235. 

non-titaniferous,  254. 

sand,  258 ;  nee  Iron  ores. 

titaniferous,  257. 
analyses,  258. 
distribution,  257. 
origin,  257. 

Maine,  molybdenum,  408 ;  topaz,  194. 
Malachite,  278,  231,  291,  293,  871. 
Malay  peninsula,  tin  from,  412. 
Maltha,  analysis  of,  60. 

Manganese,  distribution,  Arkansas,  887 ;  Cali 
fornia,  887;  Colorado,  888;  eastern 
area,  885;  Georgia,  385;  Utah,  888; 
Virginia,  886. 

in  iron  ores,  252. 

ores  of,  883. 

origin,  884. 

production,  888. 

references  on,  889. 

uses,  388. 
Marbles,  distribution  in  United  States,  81. 

general  characteristics,  78. 

See  Building  stones. 
Marl,  for  Portland  cement,  114,  119. 
Marquette  range,  261,  263. 
Marsh  gas,  in  natural  gas,  42. 

properties,  42. 
Marshes,  salt,  cause  of,  127. 
Maryland,  coal,  referred  to,  37 ;  glass  sand,  177 ; 
infusorial    earth,   162;    kaolin,    101; 
marble,  82  ;  natural  rock  cement,  118. 
Marysville,  Mont.,  887. 
Massachusetts,  emery  in,  described,  164 ;  glass 

sand,  177  ;  marble,  82 ;  pyrite,  199. 
Mechanical     concentration,     289,     810,     318, 

315. 

Mediterranean  Sea,  analysis  of  water,  124. 
Melaconite,  278,  295. 
Mendeljeff,  on  petroleum  origin,  46. 
Menominie  range,  261. 
Mercur,  Utah,  836. 
Mercury,  890. 

associated  minerals,  893. 

distribution,  California,  890;  Oregon,  392; 
Texas,  892. 

extraction,  894. 

mode  of  occurrence,  890. 

ores  of,  890. 

origin,  893. 

production  of,  394. 

references  on,  395. 

uses,  393. 

Merrill,  G.  P.,  on  chrysotUe  veins,  169. 
Mesabi  range,  Minnesota,  261,  262. 
Mesozoic,  auriferous  gravels,  827  ;  clays  of,  100; 
petroleum,  53 ;  quartzose  ores,  328. 


INDEX 


445 


Metals,  disseminated  in  granite,  226. 

disseminated  in  limestone,  226. 

disseminated  in  quartz-porphyry,  226. 

distribution  in  rocks,  226. 

precipitation,  conditions  governing,  232. 
Metasomatism,  defined,  233. 

pressure  accompanying,  233. 

temperature  during,  233. 

variation  in  process  of,  233. 
Meteoric  waters,  importance  in  secondary  con- 
centration, 230. 

Mexico,  opal  in,  195;  solfataric  sulphur  in,  196. 
Mica,  distribution,  North  Carolina,  185. 

in  kaolin,  100. 

mode  of  occurrence,  186. 

production  of,  186. 

references  on,  186. 

species  of  economic  value,  185. 

value  of,  186. 
Micanite,  185. 

Michigan,    bituminous   coal,    analysis   of,   7; 
brick  clays,  104 ;  coal  field,  28 ;  cop- 
per ores,  28T  ;  gold,  852 ;  graphite,  so- 
called,  180;  gypsum,  142;  iron  ore, 
261 ;  magnetite,  256 ;  Portland  cement 
materials,  119  ;  salt  in,  129. 
Millerite,  404. 
Millstones,  characters,  161. 

distribution,  161. 
Mine  Hill,  N.J.,  zinc  ore,  309. 
Mine  waters,  analyses  of,  227. 

vadose,  227. 
Mineral  pigments,  186. 

asbestos,  188. 

barite,  187. 

graphite,  188. 

gypsum,  187. 

hematite,  186. 

ochers,  186. 

production,  188. 

references  on,  189. 

slate,  187. 

Mineral  springs,  volume  of  discharge,  205. 
Mineral  waters,  analyses,  206. 

classification,  205. 

defined,  204. 

distribution,  205. 

origin  and  occurrence,  204. 

production  of,  206. 

references  on,  207. 

thermal  springs,  204. 
Mineralizing  vapors,  284. 

in  contact  deposits,  285. 
Minerals,  in  contact  deposits,  285. 
Minnesota,  hematite,  261,  264 ;  limonite,  271. 
Miocene,  petroleum,  58  ;  phosphate,  150. 
Mississippi,  lignite  in,  80. 
Mississippi  delta,  soils  of,  214. 
Missouri,  bituminous  coal,  analysis  of,  7 ;  ball 
clay,  103  ;  barite,  170  ;  hematite,  269  : 
Infusorial  earth,  162  ;  lime  rock,  116  ; 
stoneware  clay,  103. 


Moisture  in  coal,  8. 
Molding  sand,  analysis,  189. 

distribution,  190. 

mechanical  composition,  189. 


references  on,  190. 
Molybdenite,  339,  408. 
Molybdenum,  403. 

in  Maine,  403. 

in  western  states,  408. 

ores  and  occurrences,  408. 

production  of,  403. 

references  on,  403. 

uses,  403. 
Monazite,  analyses,  191. 

composition,  190. 

distribution,   Brazil,  190;  North  Carolina, 
190 ;  South  Carolina,  190. 

magnetic  separation  of,  191. 

occurrence,  190. 

production  of,  191. 

references  on,  191. 

uses,  191. 

Montana,  asbestos,  168  ;  silver,  284 ;  coal,  81 ; 
copper  ores,  282 ;  graphite,  179  ;  lignite 
analysis  from,  6 ;  molybdenum,  403 ; 
sapphire,  198  ;  silver-lead  ores,  878. 
Monte  Cristo,  Wash.,  835. 

direction  of  veins  at,  288. 
Montezuma,  Colo.,  zinc  concentrates,  819. 
Moss  agate,  as  gem,  195. 
Mother  lode,  California,  gold,  338. 
Muscovite,  as  source  of  mica,  185. 


Naphthas,  In  petroleum,  42. 

Natural  gas,  analyses  of,  43. 

anticlinal  theory,  48. 

distribution,    California,  56;    Indiana,  55; 
Indian   Territory,   55;    Kansas,   55; 
Kentucky,  56 ;  New  York,  54 ;  Ohio, 
55;    Pennsylvania,    54;    Texas,    66; 
West  Virginia,  55. 
exhaustion  of,  54. 
geologic  distribution,  48. 
history  of  development,  40. 
occurrence  of,  48. 
pressure  in  well,  44. 
properties  of,  42. 
references  on,  67. 
uses  of,  66. 

Natural  rock  cements,  see  Cements. 
Nebraska,  fullers  earth  in,  175. 
Nevada,  infusorial  earth,  mentioned,  162 ;  mag- 
maticaUy  segregated  ores  in,  225 ;  sol- 
fataric sulphur,  197  ;  silver-lead  ores, 
373  ;  tungsten  in,  415. 
Nevada  City,  Calif.,  834. 

Newberry,  on  temperature  petroleum  forma- 
tion, 47. 

New  Brunswick,  albertite  in,  69. 
New  Caledonia,  nickel  supply  from,  405. 


446 


INDEX 


New  England,  Infusorial  earth,  mentioned,  162. 
lime  rock  in,  116. 

New  Hampshire,  graphite  in ;  179 ;  whetstones 
mentioned,  160. 

New  Jersey,ballclay,108;  copper,296;  glass  sand, 
177 ;  greensand,  155 ;  magnetite,  256 ; 
molding  sand,  190 ;  Portland  cement 
materials,  118 ;  stoneware  clay,  103. 

New  Mexico,  anthracite  coal,  analysis  of,  8 ; 
bauxite,  379;  coal,  30,  81;  copper, 
298;  garnet,  195;  magnetite,  256; 
molybdenum,  403;  silver-lead  ores, 
873  ;  turquoise,  194 ;  vanadium,  416. 

New  York,  Clinton  ore,  266 ;  emery,  mentioned, 
164;  fuller's  earth,  175;  garnet,  163; 
graphite,  179 ;  gypsum,  142 ;  infuso- 
rial earth,  mentioned,  162 ;  limestone ; 
116 ;  magnetite,  255  ;  marble,  82 ;  mill- 
stones, 161 ;  molding  sand,  190 ;  natu- 
ral gas,  54 ;  natural  rock  cement,  118 ; 
petroleum  occurrence,  48;  Portland 
cement  materials,  118  ;  production  of 
gypsum,  145;  pyrite,  199;  salt,  127; 
siderite,  origin  of,  273 ;  sienna,  187 ; 
talc,  202  ;  whetstones,  mentioned,  160. 

New  Zealand,  magnetite  sand,  258. 

Niccolite,  404. 

Nickel  ores,  404. 

Nickel,  analysis  of,  405. 

distribution,  Missouri,  404  ;  North  Carolina, 
404;  Ontario,  Canada,  404;  Pennsyl- 
vania, 404;  western  states,  404. 
production  of,  406. 
references  on,  407. 
uses  of,  405. 

Nile  Valley,  alluvial  soils,  214. 

Nitrogen,  in  natural  gas,  214. 
in  soils,  214. 

Norite,  New  York,  78. 

North  Carolina,  asbestos,  167;  barite,  170; 
corundum,  164 ;  emerald,  198 ;  garnet, 
195 ;  graphite,  179 ;  kaolin,  101  ;  mag- 
netite, 255 ;  mica  in,  185  ;  millstones 
in,  161  ;  monazite  in,  190 ;  phosphate 
in,  154 ;  pyrophyllite,  203 ;  rubies,  193 ; 
talc,  201 ;  tin,  411 ;  Triassic  coal,  25. 

North  Dakota,  Portland  cement  materials,  119. 

Norway,  titanium  in,  418. 

Novaculite,  160. 
origin,  160. 

Nuggets,  gold,  846. 

O 

Ocher,  as  mineral  pigment,  186. 
classification,  187. 
composition,  187. 
distribution,  1ST. 
origin,  187. 

Ochsenius,  on  origin  of  salt,  125. 

Ogdensburg,  New  Jersey,  zinc  ore,  309. 

Ohio,  brick  clays,  104;  brines,  129;  Clinton 
ore,  266 ;  gypsum,  142 ;  Hocking 
Valley  coal,  analysis  of,  7 ;  molding 


sand,  190  ;  natural  gas  analysis,  43  ; 
natural  gas,  55 ;  natural  rock  cement, 
118 ;  petroleum,  50  ;  Portland  cement 
materials,  119 ;  siderite,  273 ;  stoneware 
clay,  103 ;  whetstones,  mentioned,  160. 
Oil  rock,  capacity  of,  44. 
Oil  shales,  analysis,  57. 
distillation  of,  57. 
geographic  distribution,  57. 
properties,  56. 
references  on,  67. 
Oil  springs,  52. 
Oilstones,  defined,  159. 

distribution,  160. 
Oklahoma,  gypsite  in,  142. 
Oliphant,  on  petroleum  distillates,  42. 
Ontario,  anthraxolite  in,  59. 
Ontario,  nickel,  404. 
Onyx  marbles,  83. 
characters,  83. 
distribution,  83. 
for  lithographic  work,  182. 
references  on,  91. 
Oolitic,  limestone,  defined,  80. 
Opal,  composition  and  occurrence,  195. 

distribution,  Hungary,  195;  Mexico,  195; 

Oregon,  195 ;  "Washington,  195. 
Orange  Spring,  Fla.,  205. 
Ordovician,  lead  in,  306  ;  limestones,  116. 
Ore  deposits,  bedded,  241 ;  bonanzas,  forma- 
tion of,  245;  chamber  deposits,  242; 
classification    of,    246 ;     contact   de- 
posits,  241  ;  contemporaneous  origin 
of,  224;    disseminations,  242;  Fahl- 
band,  241 ;  fissure  veins,  286 ;  forms 
of,  236 ;  impregnations,  241 ;  linked 
veins,  239 ;  ore  channel,  241 ;  origin 
of,  224;    oxidation,  243;  oxidation, 
depth  of,  244,  references  on,  249  ;  sec- 
ondary alteration  in,  242 ;  secondary 
enrichment,    245;    weathering,    242; 
weathering,  chemical   changes,  243 ; 
weathering,  conditions  affectingdepth, 
243 ;  weathering,  minerals  affected,  242. 
Oregon,  coal,  32 ;  gold  ores,  335 ;  limonite,  27  ; 
mercury,   392;   nickel,   404;  opal  in, 
195 ;  solfataric  sulphur,  197. 
Ores,  concentration  in  rocks,  225. 

value  of,  245. 

Organic  matter,  as  reducing  agent,  317. 
Oriskany,  glass  sand  in,  177  ;  limonite  in,  271 ; 

phosphate  in,  153. 
Orpiment,  898. 

Orton,  on  petroleum  origin,  47. 
Osmium,  properties  and  occurrence,  409. 
uses,  409. 

with  platinum,  407. 

Osmotic  pressure,  ore  precipitation  by,  236. 
Onray,  Colo.,  807,  842. 
Ozark  region,  314. 
Ozokerite,  properties,  59. 
occurrence,  59. 


INDEX 


447 


Palladium,  properties  and  occurrence,  409. 
uses,  409. 

with  platinum,  407. 
Paper  clay,  defined,  99. 
Paraffin,  56. 
Paragenesis,  313,  815. 
Park  City,  Utah,  807. 
Peace  River,  Fla.,  phosphate,  148. 
Peale,  on  mineral  waters,  205. 
Peat,  analyses  of,  4,  6. 
defined,  3. 
references  on,  88. 
sections  in  bog,  8. 

Peckham,  on  temperature  petroleum  forma- 
tion, 47. 

Pegmatite,  tin-bearing,  410. 
Pennsylvania,  anthracite  coal,  8,  22;  barite, 
170 ;  bituminous  coal,  7 ;  cement  ma- 
terials, 117, 118  ;  chromite,  401 ;  Clin- 
ton ore,  266 ;  copper,  296 ;  fire  clays, 
102 ;  glass  sand,  177  ;  graphite,  179  ; 
iron  ore,  256,  273  ;  kaolin,  101 ;  mag- 
netite, 256 ;  natural  gas,  54 ;  ocher, 
187  ;  petroleum,  50  ;  phosphate,  154 ; 
Portland  cement  materials,  118  ;  ser- 
pentine, 84;  siderite,  273;  sienna, 
187 ;  stoneware  clay,  103 ;  titanium, 
414;  zinc,  811. 

Penokee-Gogebic  range,  261,  262. 
Penrose,  on  Georgia  manganese,  886. 
Pentlandite,  404. 
Permian,  gypsum,  141;  rock  salt,  127;  salt, 

130. 

Persia,  turquoise,  194. 
Petroleum,  analyses,  41. 
anticlinal,  43. 
asphaltic,  40,  42. 

uses,  42. 
boiling  point,  42. 
distillates,  percentages  of,  42. 
distribution,  Alaska,  54;  Appalachian  field, 
48;    California,    52;    Colorado,    53; 
Kansas,  52 ;  Ohio-Indiana,  50 ;  Penn- 
sylvania, 50 ;  Texas-Louisiana,  61. 
flashing  point,  41. 
geologic  distribution,  48. 
gravity  of,  41. 

gushers,  in  Beaumont  field,  45. 
history  of  development,  89. 
movement  in  rocks,  47. 
nitrogen  in,  40. 
origin,  inorganic  theory,  46. 

organic  theory,  46. 
paraffin  in,  42. 
pool,  defined,  44. 
pressure  in  well,  44. 
production,  62. 
properties  of,  40. 
references  on,  66. 
rock  pressure,  45. 
sands,  defined,  44. 


solidification  temperature,  41. 

uses  of,  56. 

wells,  depth  of,  45. 
Phlogopite,  as  source  of  mica,  185. 
Phosphate,  analyses,  154. 

distribution,  Alabama,  153  ;  Arkansas,  153 ; 
Florida,  148;  Georgia,  153;  North 
Carolina,  153;  Pennsylvania,  153; 
South  Carolina,  150 ;  Tennessee,  150. 

geological  distribution,  148. 

impurities,  158. 

land  pebble,  149. 

mode  of  occurrence,  147. 

river  pebble,  149. 

rock,  148. 

soft,  149. 

uses,  154. 

Phosphoric  acid,  in  soils,  214. 
Phosphorus,  in  copper  ores,  280. 

in  iron  ores,  252. 
Pipe  clay,  defined,  99. 
Pipe  lines,  West  Virginia,  55. 
Pitches,  812. 
Placers,  827. 
Plaster  of  Paris,  144. 
Plasticity,  clay,  96. 
Platinum,  associated  metals,  407. 

composition,  407. 

distribution,  California,  408;  Wyoming, 
408. 

native,  407. 

ores,  407. 

production,  408. 

references  on,  408. 

uses,  408. 

Pleistocene,  clays,  100 ;  glass  sand,  176 ;  stone- 
ware clays,  103. 
Pneumatolysis,  defined,  284. 
Polybasite,  325,  344,  368. 
Portland  cement,  see  Cement. 
Posepny,  on  ore  deposits,  246. 

on  vadose  water,  281. 
Potash,  in  soils,  214. 

Potsdam,  glass  sand,  177 ;  sandstone,  87. 
Pottery  clay,  defined,  99. 

distribution,  103. 

Pozzuolano,  Italy,  cement  from,  111. 
Pratt,  on  chromite,  400. 

on  chrysotile  veins,  169. 

on  corundum,  168. 
Pre-Cambrian,  auriferous  gravels,  827;  clays, 

100  ;  gold,  829 ;  iron  ores,  260. 
Precious  stones,  defined,  192. 

occurrence,  192. 

production,  195. 

references  on,  195. 
Proctor,  Vt.,  marble,  82. 
Proustite,  825. 
Psilomelane,  883. 

Pulpstones,  properties  and  uses,  159. 
Pumice,  161. 

sources,  162. 


448 


INDEX. 


Pumpelly,  cited,  262. 
Pyrargyrite,  825. 
Pyrite,  2S6,  839,  871,  412. 

analysis,  199. 

as  contact  mineral,  285. 

distribution,    Massachusetts,     199 ; 
York,  199 ;  Virginia,  199. 

In  hot  spring  deposit,  228. 

occurrence,  199. 

references  on,  200. 

uses,  200. 
Pyrolusite,  888. 
Pyromorpnite,  808. 
Pyrope,  as  gem,  194. 
Pyrophyllite,  composition,  203. 

North  Carolina,  203. 

uses,  208. 

Pyroxene,  as  gangue  mineral,  295. 
Pyrrhotite,  404. 

as  contact  ore,  285. 

Ducktown,  Tenn.,  295. 

in  Virginia  pyrite  deposits,  199. 

Sudbury,  Ont.,  405. 


Quarries,  bedding  planes  In,  74. 
Quarrying,  structural  features  affecting,  74. 
Quarry  water,  73. 
Quartz,  crystalline,  uses,  168. 

in  kaolin,  100. 
Quicksilver,  390,  391,  898. 
Qulncy,  Mass.,  granite,  77. 


Realgar,  398. 

Bed  Sulphur  Springs,  Va.,  206. 

Regolitb,  213. 

Replacement,  defined,  283. 

Residual  soils,  218. 

Residuum,  petroleum,  42. 

Retort  clay,  defined,  99. 

Rhlgolene,  56. 

Rhode  Island,  coal  field,  25  ;  graphite,  179. 

Rhodium,  with  platinum,  407. 

Rico,  Colo.,  807. 

banded  veins  at,  287. 

zinc  concentrates,  819. 
Rift,  74. 
Road  materials,  21T. 

day,  behavior  under  traffic,  21T. 

gravel,  characteristics,  217. 

methods  of  testing,  218. 

references  on,  218. 

requisite  qualities,  218. 

sand,  characteristics,  217. 

shale,  217. 

Rock  crystal,  as  gem,  195. 
Rock  pressure,  Orton  on,  45. 
Eock  salt,  occurrence,  125. 
Rocky    Mountain    region,    yield    of    silver, 
882. 

coal  fields  of,  80. 


Enby,  properties,  198. 

Arizona,  193  ;  North  Carolina,  193 ;  United 

States,  193. 
Ruby  silver,  325. 
Ruthenium,  with  platinum,  407. 
Rutile,  413. 

Salina,  gypsum,  142 ;  salt,  129. 

Salines,  124. 

Sail  Mountain,  Ga.,  amphibole  asbestos,  167. 

Salt,  analyses  of  salt  and  brines,  131. 

analyses  of  sea  waters,  124. 

association  with  gypsum,  126. 

distribution,  California,  130;  Kansas,  130; 
Louisiana,  129;  Michigan,  129;  New 
York,  127 ;  Texas,  130 ;  Utah,  180. 

extraction,  181. 

impurities,  126. 

occurrence  in  waters,  124. 

production,  132. 

references  on,  134. 

rock,  origin,  125. 

sources  of,  124. 

uses,  132. 

San  Bernardino  Hot  Springs,  Calif.,  204. 
Sandberger,  on  dissemination  of  metals,  226. 
Sandstone,  84. 

arkose,  85. 

Berea,  87. 

bluestone,  85. 

distribution,  86. 

flagstone,  85. 

general  properties,  84. 

Potsdam,  87. 

varieties  of,  85. 
Sandusky,  Ohio,  gypsum,  142. 
San  Juan  region,  Colorado,  gold-silver,  841. 
Sap,  78. 
Sapphire,  198. 

distribution,  Montana,  193 ;  North  Carolina, 
193 ;  Siam,  193. 

properties,  193. 
Sagger  clay,  defined,  99. 
Saucon  Valley,  Pa.,  zinc  ores,  811. 
Scheelite,  414. 

Schrauf,  on  mercury  origin,  398. 
Sea  water,  pyrite  precipitation  from,  226. 

limonite  precipitation  from,  225. 

manganese  precipitation  from,  225. 
Selvage,  237. 

Semi-bituminous  coal,  defined,  5. 
Senarmontite,  896. 
Sericite,  826. 
Serpentine,  for  building,  88. 

characteristics,  88. 

distribution,  84. 

Seward  peninsula,  Alaska,  357 ;  tin  in,  412. 
Shale,  analysis  of,  98. 
Shutes,  237. 
Siam,  sapphire,  198. 
Siberia,  emerald,  198 ;  turquoise,  194. 
Sicily,  sulphur,  197. 


INDEX 


449 


Biderite,  272,  873. 

distribution,  Kentucky,  273;  New  York, 
278  ;  Pennsylvania,  278. 

geologic  distribution,  272. 

mode  of  occurrence,  272. 
Sienna,  defined,  187. 
Silica,  as  an  abrasive,  168. 

deposition  from  water,  893. 

effect  on  clay,  95. 

in  iron  ores,  262. 

in  soils,  214. 

Silurian,  manganese  in,  887. 
Silver,  Butte,  Mont.,  284. 

ores  of,  825. 

production,  858. 

uses  of,  857. 

with  mercury,  893. 
Silver  Cliff,  Colo.,  analyses  of  mine  waters, 

227. 

Silver  glance,  825. 
Silver  ores,  classification,  827. 

distribution  of,  see  Gold-silver. 

extraction,  829. 

geologic  distribution,  829. 

mode  of  occurrence,  826. 

production  of,  858. 

references  on,  860. 

secondary  enrichment,  327. 

wall  rocks,  826. 

weathering  of,  827. 
Silver-lead  ores,  864. 

assays  of,  872,  878. 

distribution,  Aspen,  Colo.,  867  ;  Co2ur 
d'Alene,  Ido.,  872;  Eagle  Elver, 
Colo.,  869  ;  Eureka,  Nev.,  873  ;  Glen- 
dale,  Mont.,  873;  Leadville,  Colo., 
864  ;  Neihart,  Mont.,  373  ;  New  Mex- 
ico, 373  ;  Park  City,  Utah,  8TO  ;  Bed 
Mountain,  Colo.,  869  ;  Rico,Colo.,369; 
South  Dakota,  373  ;  Ten  Mile  district, 
Colo.,  369  ;  Tintic  district,  Utah,  872. 

references  on,  874. 
Silverton,  Colo.,  841. 
Slate,  as  mineral  pigment,  187. 

quarrying,  waste  in,  88. 

uses,  89. 
Slates,  for  building,  87. 

bleaching  of,  88. 

cleavage,  87. 

distribution,  88. 

Smithsonite,  808,  305,  810,  812,  819. 
Smut,  of  coal,  16. 
Soapstone,  201. 

in  southern  Appalachians,  201. 


Soda,  in  soils,  214. 

Soda  niter,  properties,  186. 

references  on,  186. 
Sodium  sulphate,  186. 
Soils,  213. 

seolian,  214. 

alkali  in,  215. 

2r 


alluvial,  214. 

chemical  properties,  214. 

defined,  213. 

distribution,  216. 

dune,  214. 

flocculated,  215. 

glacial,  214. 

loamy,  properties,  218. 

loess,  216. 

marsh,  216. 

origin,  213. 

physical  properties,  215. 

prairie,  216. 

puddled,  215. 

references  on,  216. 

residual,  218. 

sandy,  215. 

structure,  215. 

subsoil,  216. 

temperature,  216. 

texture  of,  215. 

transported,  218. 

volcanic,  214. 

Solenhofen,  Bavaria,  lithographic  stone,  182. 
Solid  bitumens,  57. 
South  Carolina,  monazite,  190 ;  phosphate,  150 ; 

tin,  411. 

South  Dakota,  fire  clay,  103  ;  gold.  350 ;  fuller's 
earth,    175;   lithium,   183;   Portland 
cement    materials,    119;    silver-lead 
ores,  878  ;  tungsten,  415. 
Specularite,  as  contact  ore,  285. 
Sperrylite,  407. 
Spessartite,  as  gem,  194. 
Sphagnum,  8. 
Sphalerite,  303,  805,   311,  812,  818,  315,  819, 

872,  873. 

Spodumene,  188. 

Spurr,  on  magmatic  segregation,  225. 
Stannite,  410. 

Stassfurth,  Prussia,  salt  at,  126. 
Steamboat  Springs,  Nev.,  892. 
Stephanite,  825,  844. 
Stevenson,  on  anthracite  formation,  15. 


in  hot  spring  deposit,  228. 
Stoneware  clay,  analysis  of,  98. 

defined,  99. 

distribution  of,  108. 
Stream  tin,  410. 

Strontian  Island,  celestite  on,  201. 
Strontium,  minerals  containing,  200. 

references  on,  201. 

uses,  201. 
Subcarboniferous,    salt,    129 ;    limestone    for 

lime,  116;  zinc,  814. 
Subsoil,  216. 

Sudbury,  Ont.,  nickel,  405. 
Sulphides,  in  contact  deposits,  235. 
Sulphur,  distribution,  Louisiana,  197 ;  Japan, 
196;     Mexico,    196;     Oregon,    197; 
Utah,  196. 


450 


INDEX 


Sulphur  —  continued. 

geologic  age,  197. 

gypsum  type,  197. 

in  coal,  9. 

in 

origin,"  197. 

production,  198. 

references  on,  198. 

solfataric  type,  196. 

uses,  198. 

Sussex  County,  N.J.,  zinc  ores,  808. 
Sweet  Springs,  W.  Va.,  204. 
Sylvanite,  325,  839. 


Table  Mountain,  Calif.,  847. 
Talc,  201. 

analyses  of,  202. 
as  alteration  product,  201. 
distribution,  New  York,  202;  North  Caro- 
lina, 201. 

origin  and  occurrence,  201. 
production,  203. 
references  on,  203. 
uses,  202. 
Tellurides,  825. 

unknown  in  contact  deposits,  235. 
Tellurium  in  copper,  280. 
Tennantite,  285. 

Tennessee,  ball  clay,  103;  barite,  170;  fluor- 
spar, 173 ;  Jellico  coal,  analysis  of,  7 ; 
garnet,  163;  phosphate,  150;  stone- 
ware clay,  103. 

Terlingua,  Texas,  mercury,  392. 
Terra  alba,  143. 
Terra-cotta  clay,  defined,  99. 
Tertiary,  fuller's  earth,  175;  gold-silver  ores, 
887 ;  glass  sand,  177  ;  greensand,  155 ; 
lignite,  19  ;  limonite,  271 ;  phosphates, 
148,  153 ;  sulphur,  197. 
Tetrahedrite,  278,  285,  297,  321,  331,  339. 
Texas,  bat  guano,  155 ;  bituminous  coal,  analy- 
sis,   7;     coal,    29;     fertilizer,     155; 
gypsite,  142;  lignite,  6,30;  lime  rock, 
116;   limonite,   271;    mercury,   892; 
natural  gas,  56  ;  petroleum,  51 ;  Port- 
land cement  materials,  119  ;  salt,  130 ; 
stoneware  clay,  108. 
Thermal  springs,  origin,  204. 
Thorium,  in  monazite,  190, 191. 
Tin,  association  with  granite,  226. 

distribution,  Alaska,  412  ;  Black  Hills,  411 ; 
Malay  Peninsula,  412 ;  North  Caro- 
lina, 411 ;  South  Carolina,  411. 
mode  of  occurrence,  410. 
ores,  410. 

production  of,  412. 
references  on,  418. 
uses  of,  412. 
Titanic  acid,  in  clay,  96. 

Titanium,  distribution,  Norway,  418 ;  Penn- 
sylvania, 414 ;  Virginia,  414. 


in  iron  ores,  252. 
occurrence,  418. 
ores,  413. 

references  on,  414. 
uses,  414. 

Tonopah,  Nev.,  848. 

Topaz,  distribution,    Brazil,    194;    California, 
194;    Ceylon,    194;    Colorado,    194; 
Maine,  194  ;  Urals,  194. 
properties,  194. 
Torbanite,  57. 
Tourmaline,  as  gem,  195. 

with  tin,  412. 
Transported  soils,  classification,  214. 

origin,  213. 
Trap,  78. 

Travertine,  defined,  80. 
Trenton,  limestone  for  lime,  116;  petroleum 

in,  51. 

Triassic,  coal,  25;  magnetite,  256. 
Trinidad,  asphalt  in,  59. 

analysis  of,  60. 
Tripoli,  see  Infusorial  earth. 
Tully  limestone,  for  Portland  cement,  118. 
Tungsten,  analysis,  Arizona,  415. 

distribution,  Arizona,  415 ;  Black  Hills,  415 ; 
Colorado,    415;     Connecticut,    415; 
Nevada,  415. 
ores,  414. 
production,  415. 
references  on,  416. 
uses,  415. 

Turquoise,  distribution,   Arizona,    194;    Asia 
Minor,  194;  New  Mexico,  194;  Per- 
sia, 194 ;  Siberia,  194. 
properties  and  occurrence,  194. 
Type  metal,  897. 

U 

Uintaite,  69. 
Ulexite,  184. 
Umber,  defined,  187. 
Underground  waters,  207. 
references  on,  211. 
sources  of,  207. 
Urals,  topaz  in,  194. 
Uranium,  distribution,  Colorado,  416;  Utah. 

416. 

ores,  416. 
production,  416. 
references  on,  417. 
uses,  416. 

Utah,  coal,  81 ;  copper,  296 ;  desilverized  lead, 
307;  hematite,  268;  magnetite,  256; 
manganese,  888 ;  molybdenum,  40?  ; 
Portland  cement  materials,  119  ;  salt, 
130;  silver-lead  ores,  372;  sulphur, 
196 ;  uranium,  416. 


Vadose  water,  defined,  227. 
Vanadium,  distribution,   Arizona,   416;  New 
Mexico.  416. 


INDEX 


451 


Vanadium  —  continued, 

ores,  416. 

production,  416. 

references  on,  417. 

uses,  416. 
Van  Hise,  on  Lake  Superior  ores,  262. 

on  meteoric  waters,  228. 

on  ore  deposit  classification,  246. 
Veins,  see  Fissure  veins. 
Vermilion,  as  mineral  pigment,  188. 
Vermilion  Range,  Minn.,  261.  264. 
Vermont,  asbestos,  168 ;    marble,   82 ;    -whet- 
stones, 160. 

Vesuvianite,  in  contact  deposits,  235. 
Virgilina,  Va.,  copper,  291. 
Virginia,  arsenic,  398;  asbestos,  107;  barite, 
170 ;   brines,   129  ;    coal,  25 ;    green- 
sand,  155;  gypsum,    142;    infusorial 
earth,    162 ;    kaolin,    101 ;    limonite, 
271 ;  pyrite,  199  ;  titanium,  414. 
Virginia  City,  Nev.,  344. 
Vogt,  on  magmatic  segregation,  224. 
Volcanic  ash,  161. 

United  States  deposits,  162. 

soils,  214. 

W 

Wad,  383. 

Warm  Springs,  Tenn.,  204. 
Warm  Sulphur  Springs,  Va.,  205. 
Washington,  arsenic,  398 ;   bituminous   coal, 
analysis  of,  8 ;  coals,  82 ;  gold,  835 ; 
lignite,    analysis,    6 ;     molybdenum, 
403 ;  nickel,  404. 
Water,  artesian,  209. 

as  carrier  of  ores,  226. 

circulation  of  meteoric,  229. 

distribution  in  earth's  crust,  228. 

hot,  agent  in  ore  formation,  228. 

in  clay,  96. 

mine,  analyses,  227. 

mineral,  205. 

of  igneous  origin,  229. 

of  meteoric  origin,  228. 

underground,  source  of,  228. 
Water  lime  beds,  cement  rock  in,  117. 
Water  table,  208. 

Watson,  on  Georgia  manganese,  386. 
Weathering,  building  stones,  70,  75,  79,  85. 

ore  deposits,  242. 
Weed,  cited,  228,  280,  246. 


West  Virginia,  brines,  129  ;  gas,  55 ;  glass  sand, 

177 ;  grahamite,  59  ;  natural  gas,  55 ; 

petroleum,  48. 
Westerly,  E.I.,  granite,  77. 
Whetstones,  defined,  159. 

distribution,  160. 

White,  I.  C.,  on  anticlinal  theory,  48. 
White  lead,  as  mineral  pigment,  188. 
White  metal,  320. 
Whiting,  as  mineral  pigment,  188. 
Whitney,  on  Lake  Superior  ores,  262. 
Willemite,  303,  804,  308,  310. 
Winslow,  on  Missouri  lead  and  zinc,  226. 
Wisconsin,  Clinton   ore,  266;   graphite,   180; 

hematite,  261,  264;   limomite,    271; 

natural  rock  cement,  118;  zinc  ores, 

812. 

Wolframite,  414. 
Wollastonite,  235. 
Wulfenite,  403. 
Wyoming,  asbestos,  168  ;  copper,  298  ;  gypsitc, 

142;  hematite,  268;  magnetite,  256; 

nickel,  404 ;  petroleum,  53 ;  platinum, 

408. 

Y 

Yellow  ocher,  see  Ocher. 
Yukon  valley,  Alaska,  358. 


Zinc,  Butte,  Mont.,  285. 
ores  of,  808. 
production  of,  821. 
with  mercury,  898. 
uses  of,  320. 
Zincite,  303,  308,  810. 
Zinc  ores,  analysis  of,  Leadville,  818. 
Missouri,  815. 
New  Jersey,  308. 

distribution,  Creede,  Colo.,  819  ;  Iowa,  311 ; 
Missouri,  314 ;  New  Jersey,  808 ;  New 
Mexico,  819  ;  Pennsylvania,  311 ;  Vir- 
ginia-Tennessee, 809 ;  Wisconsin,  311. 
impurities  in,  304. 
mechanical  concentration,  313. 
references  on,  828. 
residual,  310. 
superficial  alteration,  305. 
Zinc  oxide,  manufacture  in  Colorado,  818. 
Zone  of  flowage,  228. 
Zone  of  fracture,  228. 


ELEMENTARY  GEOLOGY. 


RALPH  STOCKMAN  TARR>  B.S.,  F.G.S.A., 

Professor  of  Dynamic    Geology  and   Physical    Geography  at  Cornell  University^ 
Author  of  "Economic   Geology  of  the  United  State*,"  ttc 


I2tno.    Cloth.    486  pp.    Price  $1.40  net. 


COMMENTS  OF  THE  PRESS. 

"  We  do  not  remember  to  have  noted  a  text-book  of  geology  which 
seems  to  so  go  to  the  heart  of  the  matter."  —  Phila.  Evening  Bulletin. 

"The  author's  style  is  clear,  direct,  and  attractive.  In  short,  he  has 
done  his  work  so  well  that  we  do  not  see  how  it  could  have  been  done 
better."  —  Journal  of  Pedagogy. 

"  It  is  far  in  advance  of  all  geological  text-books,  whether  American 
or  European,  and  it  marks  an  epoch  in  scientific  instruction." 

—  The  American  Geologist. 

"The  student  is  to  be  envied  who  can  begin  the  study  of  this  deeply 
interesting,  fascinating  subject  with  such  an  attractive  help  as  this 
text-book." — Wooster  Post-Graduate. 

"The  Geology  is  admirably  adapted  for  its  purpose — that  of  a  text- 
book." —  Brooklyn  Standard  Union. 

"  So  admirable  an  exposition  of  the  science  as  is  found  in  this  book 
must  be  welcomed  both  by  instructors  and  students.  The  arrange- 
ment of  facts  is  excellent,  the  presentation  of  theory  intelligent  and 
progressive,  and  the  style  exceedingly  attractive."  —  N.  Y.  Tribune. 


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NEW  PHYSICAL  GEOGRAPHY 

BY 

RALPH  STOCKMAN  TARR,  B.S.,  P.G.S.A. 

Pro/tssor  in  Cornell  University,  and  co-author  of  the  Tarr  and  McMurry  Geographies 


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Modern.  This  being  the  latest  book  on  the  subject,  the  author  has 
been  able  to  describe  the  results  of  the  most  recent  investigations  into 
important  physical  phenomena,  such  as  the  eruption  of  Mont  Pelde. 

Arrangement.  For  the  first  time  a  text-book  in  the  science  has  been 
prepared  that  proceeds  from  the  simple  to  the  complex.  The  study  of 
springs,  rivers,  valleys,  mountains,  and  hills  introduces  the  pupil  to  the 
study,  while  the  study  of  the  atmosphere,  the  weather,  and  more  diffi- 
cult subjects  is  presented  near  the  end  of  the  book. 

Application.  As  each  new  principle  is  presented,  it  is  applied  to 
definite  localities  with  which  the  pupil  is  already  acquainted.  This 
method  increases  the  child's  interest  in  the  study. 

Illustrations.  There  are  568  photographs  of  the  places  mentioned 
in  the  text.  Next  to  being  on  the  ground,  these  views  are  the  best  aid 
to  teacher  and  pupil.  No  other  text-book  can  compare  with  Professor 
Tarr's  work  in  this  feature. 

Human  Element.  In  the  chapters  on  the  Physiography  of  the 
United  States,  Rivers  of  the  United  States,  Distribution  of  Plants, 
Distribution  of  Animals,  and  Man  and  Nature,  the  effects  and  opera- 
tions of  physiographic  laws  are  clearly  and  interestingly  shown. 

Teachable.  By  means  of  a  summary  at  the  close  of  each  paragraph, 
of  Review  Questions  and  Topics  at  the  end  of  each  chapter,  and  of 
simple  home  experiment  directions,  the  book  becomes  by  far  the  sim- 
plest high-school  text-book  on  the  market. 


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64-66  FIFTH  AVENUE,   NEW  YORK 
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ELEMENTARY  PHYSICAL 
GEOGRAPHY 


BY 


RALPH  STOCKMAN  TARR,  B.S.,  F.G.S.A. 

Professor   of  Dynamic    Geology    and   Physical    Geography  at    Cornell    University; 
Author  of  "Economic   Geology  of  the   United  States,"  etc. 


Fifth  Edition,  Revised      i2mo     Cloth      $1.40  net 


"  There  is  an  advanced  and  modernized  phase  of  physical  geography, 
however,  which  the  majority  of  the  committee  prefer  to  designate  physi- 
ography, not  because  the  name  is  important,  but  because  it  emphasizes 
a  special  and  important  phase  of  the  subject  and  of  its  treatment.  The 
scientific  investigations  of  the  last  decade  have  made  very  important  addi- 
xions  to  the  physiographic  knowledge  and  methods  of  study.  These  are 
indeed  so  radical  as  to  be  properly  regarded,  perhaps,  as  revolutionary." 

"  The  majority  of  the  Conference  wish  to  impress  upon  the  attention 
of  the  teachers  the  fact  that  there  has  been  developed  within  the  past 
decade  a  new  and  most  important  phase  of  the  subject,  and  to  urge  that 
they  hasten  to  acquaint  themselves  with  it  and  bring  it  into  the  work  of 
the  school-room  and  of  the  field."  —  Report  of  Geography  Conference  to 
the  Committee  of  Ten. 

The  phenomenal  rapidity  with  which  Tarr's  Elementary  Physical 
Geography  has  been  introduced  into  the  best  high  schools  of  this  coun- 
try is  a  fact  familiar  to  the  school  public.  The  reason  should,  by  this 
time,  be  equally  familiar  —  the  existence  of  a  field  of  school  work  in 
which,  until  the  appearance  of  Tarr's  book,  there  was  not  a  single  ade- 
quate or  modern  American  text-book.  That  such  a  field  did  exist,  is 
simply  shown  by  the  paragraphs  reprinted  above.  The  adoption  of  the 
book  in  such  important  high  schools  as  those  of  Chicago,  and  the 
expressions  of  approval  from  representative  New  England  schools,  will 
indicate  how  well  the  field  has  been  covered. 


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UNIVERSITY  OF  CALIFORNIA  LIBRARY 

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